fix(sync): dashboard sync covers current year plus Nov-Dec of previous

/sync-bank now uses one shared default window in both implementations:
1 November of the previous year to 31 December of the current year.
Payments dated around New Year are picked up in January; duplicates
are still filtered by Sync ID.

Python used a hardcoded 2026 window and would have stopped syncing on
2027-01-01; Go used the current calendar year only.

Adds make sync-year [YEAR=N] with the same window. The CLI default
without flags (last 30 days) is unchanged.

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

go/cmd/fuj/main.go

@@ -92,9 +92,7 @@ func serverCmd(args []string) {
 
 	actions := web.ActionHandlers{
 		BankSync: func(ctx context.Context, out io.Writer) error {
-			yr := time.Now().Year()
-			from := time.Date(yr, 1, 1, 0, 0, 0, 0, time.UTC)
-			to := time.Date(yr, 12, 31, 23, 59, 59, 0, time.UTC)
+			from, to := banksync.DefaultWindow(time.Now())
 
 			fmt.Fprintln(out, "=== Sync Fio Transactions ===")
 			n, err := banksync.SyncToSheets(ctx, config.PaymentsSheetID, fioClients, sheetsCli,