QA hardening: security RLS fixes, Flutter 3.47.5 upgrade, UI/validation fixes

Security — enforce write authorization server-side (was UI/RPC-only):
- it_service_requests RLS: block cross-office read/edit + self-approve (QA-015)
- pass_slips RLS: owner can complete but not self-approve (QA-046)
- swap_requests RLS: scope select/update to participants + admin (QA-047)
- storage: tighten it_service_attachments + task_attachments write/delete (QA-027)
- admin_user_management edge function: allow programmers to manage users (QA-016)

Fixes:
- workforce generator "uncovered shifts" false alarms (QA-043/044)
- network-map VLAN + New-location dialog validation, disabled-until-valid (QA-048)
- de-flake time-of-day-dependent dashboard metrics test (QA-045)

Toolchain:
- upgrade to Flutter 3.47.5 / Dart 3.13.4; font_awesome_flutter 11.0.0,
  flutter_quill 11.6.0, pdfrx 2.6.5; clear resulting deprecations (QA-002)

analyze clean; 139 tests pass; web build succeeds. Report + evidence in docs/qa/.

Note: also carries the in-progress Brick model cleanup already present in the
working tree. QA-001 (AI keys public in the build) is deferred by owner decision.

Co-Authored-By: claude-flow <ruv@ruv.net>

lib/widgets/update_dialog.dart

@@ -5,6 +5,7 @@ import 'package:flutter_quill/flutter_quill.dart' as quill;
 
 import '../models/app_version.dart';
 import '../services/app_update_service.dart';
+import '../utils/snackbar.dart';
 
 /// A reusable dialog that can render both flexible and forced updates and
 /// report download progress.  Callers should wrap this with `showDialog` and
@@ -47,9 +48,7 @@ class _UpdateDialogState extends State<UpdateDialog> {
         _failed = true;
         _downloading = false;
       });
-      ScaffoldMessenger.of(
-        context,
-      ).showSnackBar(SnackBar(content: Text('Download failed: $err')));
+      showErrorSnackBar(context, 'Download failed: $err');
     }
   }