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/utils/app_time.dart

@@ -29,6 +29,16 @@ class AppTime {
     return toAppTime(DateTime.parse(value));
   }
 
+  /// "Just now", "5m ago", "3h ago", "2d ago", then a short date after a week.
+  static String relative(DateTime value) {
+    final diff = now().difference(value);
+    if (diff.inMinutes < 1) return 'Just now';
+    if (diff.inMinutes < 60) return '${diff.inMinutes}m ago';
+    if (diff.inHours < 24) return '${diff.inHours}h ago';
+    if (diff.inDays < 7) return '${diff.inDays}d ago';
+    return formatDate(value);
+  }
+
   /// Converts a [DateTime] into a human-readable short date string.
   ///
   /// Example: **Jan 05, 2025**. This matches the format previously used by