v1.6.5: fix attendance unique constraint, schema sync, seed script

- Change attendance idx_attendance_user_date from unique to index (allow multiple shifts per day)
- Reset migrations to single baseline init migration
- Add seed script with admin user (admin/admin)
- Update CLAUDE.md with migration workflow documentation
- Various frontend fixes (queries, pages, hooks)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/admin/pages/LeaveApproval.tsx

@@ -158,6 +158,8 @@ export default function LeaveApproval() {
       if (result.success) {
         setApproveModal({ open: false, request: null });
         await queryClient.invalidateQueries({ queryKey: ["leave"] });
+        await queryClient.invalidateQueries({ queryKey: ["leave-requests"] });
+        await queryClient.invalidateQueries({ queryKey: ["attendance"] });
         alert.success("Žádost byla schválena");
       } else {
         alert.error(result.error);
@@ -195,6 +197,8 @@ export default function LeaveApproval() {
         setRejectModal({ open: false, request: null });
         setRejectNote("");
         await queryClient.invalidateQueries({ queryKey: ["leave"] });
+        await queryClient.invalidateQueries({ queryKey: ["leave-requests"] });
+        await queryClient.invalidateQueries({ queryKey: ["attendance"] });
         alert.success("Žádost byla zamítnuta");
       } else {
         alert.error(result.error);