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>

app/Notifications/DeclarationOverdueNotification.php

@@ -51,6 +51,7 @@ class DeclarationOverdueNotification extends Notification implements ShouldQueue
                 'declarationTitle' => $this->declaration->title ?? 'Sans titre',
                 'dueDate' => $this->declaration->due_date?->format('d/m/Y'),
                 'url' => route('declarations.show', $this->declaration),
+                'firmName' => $this->declaration->workspace?->name,
             ]);
     }
 }