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>

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),