fix: skip untracked workdays when closing a week

Previously any past workday without a closed_days record blocked week
close. Now only days that actually have entries require an explicit
close. Empty workdays count as 0h worked, which is reflected in the
weekly delta automatically.

- WeekService.CloseWeek: after finding no closed_days record, check
  whether the day has any entries; only error if it does
- NewWeekService: takes EntryStore to support the above check
- Updated TestCloseWeekMissingDayFails to reflect the new semantic
  (test now creates entries on Friday but leaves it unclosed)

cmd/wotra/main.go

@@ -48,7 +48,7 @@ func main() {
 	entrySvc := service.NewEntryService(entryStore, closedDayStore, settingsStore, tz)
 	daySvc := service.NewDayService(entryStore, closedDayStore, settingsStore, tz)
 	settingsSvc := service.NewSettingsService(settingsStore)
-	weekSvc := service.NewWeekService(closedDayStore, closedWeekStore, settingsStore, db, tz)
+	weekSvc := service.NewWeekService(closedDayStore, closedWeekStore, entryStore, settingsStore, db, tz)
 
 	// Background goroutine: auto-stop entries that cross midnight
 	ctx, cancel := context.WithCancel(context.Background())