feat: add bulk client notifications and email enhancements with review fixes (Stories 3.4 & 3.5)

Story 3-4: Bulk client notification scheduling — BulkNotificationController,
BulkActionBar component, checkbox selection on declarations index.

Story 3-5: Email notification enhancement — observer-driven email on
en_attente_client, cache invalidation on ferme, workspace branding on
all email templates, 11 feature tests.

Code review fixes:
- Move bulk-notify route above resource wildcard to prevent shadowing
- Add static $suppressEmail flag to prevent observer double-sending
  when DeclarationMessageController already sends the email
- Fix canBulkNotify logic (was granting workers access)
- Add WorkspaceUserRole check to BulkNotifyRequest::authorize()
- Replace firstOrCreate with explicit invitation lookup that syncs
  client email and handles used/expired invitations correctly
- Watch declarations.data instead of current_page to clear selection
  on filter/sort changes

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

_bmad-output/implementation-artifacts/sprint-status.yaml

@@ -35,6 +35,10 @@
 
 generated: 2026-03-11
 last_updated: "2026-03-26"
+# Story 3-5 dev completed: 2026-03-26
+# Story 3-5 contexted: 2026-03-26
+# Story 3-4 dev started: 2026-03-26
+# Story 3-4 contexted: 2026-03-26
 project: "l'ami fiduciaire"
 project_key: NOKEY
 tracking_system: file-system
@@ -72,9 +76,9 @@ development_status:
   epic-3: in-progress
   3-1-notification-infrastructure-setup: done
   3-2-one-click-nudge-system: done
-  3-3-notification-center-and-bell: review
-  3-4-bulk-client-notification-scheduling: backlog
-  3-5-email-notification-enhancement-for-key-events: backlog
+  3-3-notification-center-and-bell: done
+  3-4-bulk-client-notification-scheduling: done
+  3-5-email-notification-enhancement-for-key-events: review
   epic-3-retrospective: optional
 
   # Epic 4: Bulk Operations, Search & Advanced Filtering