refactor: move Python implementation to legacy/, make Go primary

Go (go/) becomes the primary implementation. The original Python
version moves to legacy/ and is kept runnable; new features are still
built in both (see the Dual implementation rule in CLAUDE.md).

- git mv app.py, scripts/, templates/, tests/, pyproject.toml, uv.lock
  and build/ into legacy/
- Makefile: Python targets point at legacy/, venv in legacy/.venv,
  CREDENTIALS_PATH exported for the root .secret/ file
- CI and make image build the Python image with legacy/ as context;
  the Makefile is no longer copied into the image
- legacy/.dockerignore moved to the context root so it takes effect
- CLAUDE.md, docs/README.md, Go comments, fixture README, capture
  script and VS Code launch config updated to the new layout

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

go/internal/domain/czech/parse_month_references_test.go

@@ -9,7 +9,7 @@ func TestParseMonthReferences(t *testing.T) {
 	t.Parallel()
 
 	// All expected outputs verified against live Python implementation on 2026-05-05:
-	//   PYTHONPATH=scripts:. python -c 'from czech_utils import parse_month_references; print(parse_month_references("<input>", 2026))'
+	//   PYTHONPATH=legacy/scripts:legacy python -c 'from czech_utils import parse_month_references; print(parse_month_references("<input>", 2026))'
 	tests := []struct {
 		name        string
 		input       string

go/internal/domain/fees/fees.go

@@ -1,4 +1,4 @@
-// Package fees ports fee calculation from scripts/attendance.py.
+// Package fees ports fee calculation from legacy/scripts/attendance.py.
 package fees
 
 const (
@@ -6,7 +6,7 @@ const (
 	AdultFeeSingle  = 200 // CZK for exactly 1 practice
 )
 
-// AdultFeeMonthlyRate mirrors ADULT_FEE_MONTHLY_RATE in scripts/attendance.py.
+// AdultFeeMonthlyRate mirrors ADULT_FEE_MONTHLY_RATE in legacy/scripts/attendance.py.
 // Months absent from this map fall back to AdultFeeDefault.
 var AdultFeeMonthlyRate = map[string]int{
 	"2025-09": 750, "2025-10": 750, "2025-11": 750, "2025-12": 750,

go/internal/domain/fees/junior.go

@@ -2,7 +2,7 @@ package fees
 
 const JuniorFeeDefault = 500 // CZK fallback for 2+ practices when month not in JuniorFeeMonthlyRate
 
-// JuniorFeeMonthlyRate mirrors JUNIOR_MONTHLY_RATE in scripts/attendance.py.
+// JuniorFeeMonthlyRate mirrors JUNIOR_MONTHLY_RATE in legacy/scripts/attendance.py.
 // Months absent from this map fall back to JuniorFeeDefault.
 var JuniorFeeMonthlyRate = map[string]int{
 	"2025-09": 250,

go/internal/domain/matching/doc.go

@@ -1,2 +1,2 @@
-// Package matching ports name/member matching from scripts/match_payments.py.
+// Package matching ports name/member matching from legacy/scripts/match_payments.py.
 package matching

go/internal/domain/matching/format_date.go

@@ -14,7 +14,7 @@ var sheetsEpoch = time.Date(1899, 12, 30, 0, 0, 0, 0, time.UTC)
 // a pre-formatted "YYYY-MM-DD" string (returned as-is), or any other value
 // (returned as fmt.Sprint(v).TrimSpace). Never returns an error.
 //
-// Ports scripts/match_payments.py format_date.
+// Ports legacy/scripts/match_payments.py format_date.
 func FormatDate(val any) string {
 	if val == nil {
 		return ""

go/internal/domain/matching/format_date_test.go

@@ -1,8 +1,8 @@
 package matching
 
-// Expected values verified against scripts/match_payments.py on 2026-05-06:
+// Expected values verified against legacy/scripts/match_payments.py on 2026-05-06:
 //
-//	PYTHONPATH=scripts:. python3 -c '
+//	PYTHONPATH=legacy/scripts:legacy python3 -c '
 //	from match_payments import format_date
 //	for v in [None, "", 44197, 44197.5, "2026-04-15", "garbage", "  2026-04-15  "]:
 //	    print(repr(format_date(v)))

go/internal/domain/matching/infer.go

@@ -33,7 +33,7 @@ type InferredDetails struct {
 // defaultYear seeds czech.ParseMonthReferences (Python defaulted to the current year;
 // callers should pass time.Now().Year() or a fixed year for deterministic tests).
 //
-// Ports scripts/match_payments.py infer_transaction_details.
+// Ports legacy/scripts/match_payments.py infer_transaction_details.
 func InferTransactionDetails(tx Transaction, memberNames []string, defaultYear int) InferredDetails {
 	searchText := fmt.Sprintf("%s %s %s", tx.Sender, tx.Message, tx.UserID)
 

go/internal/domain/matching/infer_test.go

@@ -1,8 +1,8 @@
 package matching
 
-// Expected values verified against scripts/match_payments.py on 2026-05-06:
+// Expected values verified against legacy/scripts/match_payments.py on 2026-05-06:
 //
-//	PYTHONPATH=scripts:. python3 << 'EOF'
+//	PYTHONPATH=legacy/scripts:legacy python3 << 'EOF'
 //	from match_payments import infer_transaction_details
 //	MEMBERS = ["Tomáš Němeček (Tov)", "Jana Nováková"]
 //	cases = [

go/internal/domain/matching/match_members.go

@@ -28,7 +28,7 @@ var commonSurnames = map[string]bool{
 // MatchMembers finds members mentioned in text and returns them with a
 // confidence level of "auto" (reliable) or "review" (needs human verification).
 //
-// Algorithm (ported verbatim from scripts/match_payments.py match_members):
+// Algorithm (ported verbatim from legacy/scripts/match_payments.py match_members):
 //  1. Exact short-circuit: if any member's full normalized name appears as whole
 //     words in normalize(text), return ONLY those matches as auto. This prevents
 //     nickname "tov" from matching inside surname "ottova".

go/internal/domain/matching/match_members_test.go

@@ -1,9 +1,9 @@
 package matching
 
-// Expected values verified against scripts/match_payments.py and
+// Expected values verified against legacy/scripts/match_payments.py and
 // tests/test_match_members.py on 2026-05-06:
 //
-//	PYTHONPATH=scripts:. python3 -c '
+//	PYTHONPATH=legacy/scripts:legacy python3 -c '
 //	from match_payments import match_members
 //	MEMBERS = ["Henrietta Ottová", "Tomáš Němeček (Tov)", "František Vrbík (Štrúdl)", "Jana Nováková"]
 //	cases = [

go/internal/domain/matching/name_variants.go

@@ -19,7 +19,7 @@ var (
 // this invariant for the exact short-circuit pass. Variants shorter than 3 characters are
 // dropped.
 //
-// Ports scripts/match_payments.py _build_name_variants.
+// Ports legacy/scripts/match_payments.py _build_name_variants.
 func BuildNameVariants(name string) []string {
 	var nickname string
 	if m := nicknameRe.FindStringSubmatch(name); m != nil {

go/internal/domain/matching/name_variants_test.go

@@ -1,8 +1,8 @@
 package matching
 
-// Expected values verified against scripts/match_payments.py on 2026-05-06:
+// Expected values verified against legacy/scripts/match_payments.py on 2026-05-06:
 //
-//	PYTHONPATH=scripts:. python3 -c '
+//	PYTHONPATH=legacy/scripts:legacy python3 -c '
 //	from match_payments import _build_name_variants
 //	for n in ["František Vrbík (Štrúdl)", "Tov (St)", "Jana", "  Petr  Novák  ( Jenda ) "]:
 //	    print(repr(n), "->", _build_name_variants(n))

go/internal/domain/money/money.go

@@ -1,4 +1,4 @@
-// Package money ports Czech-locale currency parsing from scripts/infer_payments.py.
+// Package money ports Czech-locale currency parsing from legacy/scripts/infer_payments.py.
 package money
 
 import (
@@ -11,7 +11,7 @@ import (
 var ErrInvalidAmount = errors.New("money: invalid CZK amount")
 
 // ParseCZK parses a Czech-locale amount string and returns the value in CZK
-// as a float64. Mirrors scripts/infer_payments.py parse_czk_amount:
+// as a float64. Mirrors legacy/scripts/infer_payments.py parse_czk_amount:
 //
 //   - empty input → (0, nil)
 //   - "Kč"/"CZK" suffixes stripped (case-sensitive, like Python)

go/internal/domain/money/money_test.go

@@ -8,7 +8,7 @@ func TestParseCZK(t *testing.T) {
 	t.Parallel()
 
 	// All expected outputs verified against live Python implementation on 2026-05-06:
-	//   PYTHONPATH=scripts:. python -c '
+	//   PYTHONPATH=legacy/scripts:legacy python -c '
 	//   from infer_payments import parse_czk_amount
 	//   for v in [None, "", "0", "500", "500 Kč", "500 CZK",
 	//             "1 500", "1500.00", "1 500.00",

go/internal/domain/reconcile/reconcile.go

@@ -1,4 +1,4 @@
-// Package reconcile ports the three-phase payment reconciliation from scripts/match_payments.py.
+// Package reconcile ports the three-phase payment reconciliation from legacy/scripts/match_payments.py.
 package reconcile
 
 import (
@@ -105,7 +105,7 @@ var questionMarkRe = regexp.MustCompile(`\[\?\]\s*`)
 
 // canonicalMemberKey returns a diacritic-, case-, and whitespace-insensitive key
 // used to resolve Person-column values that drift from canonical attendance-sheet names.
-// Ports scripts/match_payments.py canonical_member_key.
+// Ports legacy/scripts/match_payments.py canonical_member_key.
 func canonicalMemberKey(name string) string {
 	return strings.Join(strings.Fields(czech.Normalize(name)), " ")
 }
@@ -124,7 +124,7 @@ type monthExpected struct {
 // defaultYear seeds czech.ParseMonthReferences in the inference fallback.
 // Pass time.Now().Year() in production; pass a fixed year in tests.
 //
-// Ports scripts/match_payments.py reconcile.
+// Ports legacy/scripts/match_payments.py reconcile.
 func Reconcile(
 	members []Member,
 	sortedMonths []string,

go/internal/domain/reconcile/reconcile_test.go

@@ -1,8 +1,8 @@
 package reconcile
 
-// Expected values verified against scripts/match_payments.py on 2026-05-06:
+// Expected values verified against legacy/scripts/match_payments.py on 2026-05-06:
 //
-//	PYTHONPATH=scripts:. python3 -m unittest tests.test_reconcile_exceptions tests.test_match_payments -v
+//	PYTHONPATH=legacy/scripts:legacy python3 -m unittest tests.test_reconcile_exceptions tests.test_match_payments -v
 //
 // All Python test cases are ported below. Additional Go-only cases are marked with [Go].
 

go/internal/domain/synch/synch.go

@@ -1,5 +1,5 @@
 // Package synch ports the bank-sync deduplication helper from
-// scripts/sync_fio_to_sheets.py.
+// legacy/scripts/sync_fio_to_sheets.py.
 package synch
 
 import (
@@ -30,7 +30,7 @@ type Transaction struct {
 // "date|amount|currency|sender|vs|message|bank_id" (lower-cased), used
 // as the dedup key in column K of the payments sheet.
 //
-// Byte-stable with scripts/sync_fio_to_sheets.py generate_sync_id.
+// Byte-stable with legacy/scripts/sync_fio_to_sheets.py generate_sync_id.
 func GenerateSyncID(tx Transaction) string {
 	currency := tx.Currency
 	if currency == "" {

go/internal/domain/synch/synch_test.go

@@ -6,7 +6,7 @@ import (
 
 // All expected digests verified against the live Python implementation on 2026-05-06:
 //
-//	PYTHONPATH=scripts:. python -c '
+//	PYTHONPATH=legacy/scripts:legacy python -c '
 //	from sync_fio_to_sheets import generate_sync_id
 //	cases = [
 //	    {"date":"2026-01-15","amount":500.0,"currency":"CZK","sender":"Jan Novak","vs":"123","message":"clenske 1/2026","bank_id":"abc123"},
@@ -88,7 +88,7 @@ func TestGenerateSyncID(t *testing.T) {
 
 // All expected strings verified against the live Python implementation on 2026-05-06:
 //
-//	PYTHONPATH=scripts:. python -c '
+//	PYTHONPATH=legacy/scripts:legacy python -c '
 //	for v in [0.0, 500.0, -500.0, 0.1, 1234.56, 99999.99, 1500000.0, 1e16, 1e-5]:
 //	    print(repr(v), "->", repr(str(v)))
 //	'