fix: migration

internal/service/reminder_service.go

@@ -105,9 +105,11 @@ func (s *ReminderService) SetEnabled(ctx context.Context, userID string, enabled
 }
 
 // SetTimezone validates the IANA zone before storing so a bad value can never
-// break the (timezone-using) candidate scan.
+// break the (timezone-using) candidate scan. Legacy aliases are canonicalized
+// first (browsers report e.g. "Asia/Calcutta"): Go resolves them but a
+// Postgres without the tzdata backward links rejects them in AT TIME ZONE.
 func (s *ReminderService) SetTimezone(ctx context.Context, userID, tz string) error {
-	tz = strings.TrimSpace(tz)
+	tz = canonicalTZ(strings.TrimSpace(tz))
 	if tz == "" {
 		tz = "UTC"
 	}