fix(py): coerce VS column to string in payments tx projection

The Sheets API returns VS (variabilní symbol) cells as float64 when
the column is number-formatted, so Python was emitting vs: 0 (a JSON
number) while Go's getVal uses fmt.Sprint and always emits vs: "0"
(a string). Add get_str helper that converts whole-number floats via
int() first (matching Go's %g formatting), applied to the vs field.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 2026-05-07 23:51 CEST — feat(py): M5.4 fix #2 — add vs and sync_id to payments tx projection
+
+- `scripts/match_payments.py`: `fetch_sheet_data` now reads `VS` and `Sync ID` columns and includes `vs`/`sync_id` keys in every tx dict. Previously only 9 columns were projected, causing `make parity` to report extra `vs`/`sync_id` fields on every raw payment row emitted by the Go backend. Values flow through `group_payments_by_person` → `_unwrap_view_model_for_api` to `raw_payments` (adults/juniors) and `grouped_payments` (payments) automatically.
+- `tests/test_app.py`: updated `/api/*` mock fixtures to include `vs`/`sync_id` keys for realism.
+- **Cache note**: after deploying, hit `POST /flush-cache` once so the in-process cache is cleared and the next request picks up the new column lookups.
+
 ## 2026-05-07 23:37 CEST — fix(go): accept single-digit day/month in attendance date headers
 
 - `go/internal/services/membership/sources.go`: `parseDates` now uses Go time formats `2.1.2006` and `1/2/2006` (single-digit reference forms, which accept both padded and unpadded inputs) instead of `02.01.2006` and `01/02/2006`. The Czech attendance sheet headers contain dates like `1.6.2026`, `23.3.2026`, `6.4.2026` — Go silently dropped those columns under the strict zero-padded format, while Python's `strptime("%d.%m.%Y")` accepted them. Effect was a missing `2026-06` month entirely on `/api/juniors` plus undercounted attendance for any month with single-digit columns; both surfaced as diffs in `make parity`.

scripts/match_payments.py

@@ -249,6 +249,12 @@ def fetch_sheet_data(spreadsheet_id: str, credentials_path: str) -> list[dict]:
         def get_val(idx):
             return row[idx] if idx != -1 and idx < len(row) else ""
 
+        def get_str(idx):
+            v = get_val(idx)
+            if isinstance(v, float) and v.is_integer():
+                return str(int(v))
+            return str(v)
+
         tx = {
             "date": format_date(get_val(idx_date)),
             "amount": get_val(idx_amount),
@@ -257,7 +263,7 @@ def fetch_sheet_data(spreadsheet_id: str, credentials_path: str) -> list[dict]:
             "purpose": get_val(idx_purpose),
             "inferred_amount": get_val(idx_inferred_amount),
             "sender": get_val(idx_sender),
-            "vs": get_val(idx_vs),
+            "vs": get_str(idx_vs),
             "message": get_val(idx_message),
             "bank_id": get_val(idx_bank_id),
             "sync_id": get_val(idx_sync_id),