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/offers.css

@@ -601,6 +601,14 @@
   color: var(--text-muted) !important;
 }
 
+/* Completed offer */
+.offers-completed-row {
+  background: var(
+    --row-completed,
+    color-mix(in srgb, var(--success) 8%, transparent)
+  );
+}
+
 /* Read-only form (invalidated offer detail) */
 .offers-readonly input[readonly],
 .offers-readonly select:disabled {