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/Mail/DeclarationFileRequestMail.php

@@ -45,6 +45,7 @@ class DeclarationFileRequestMail extends Mailable
                 'body' => $this->body,
                 'uploadUrl' => route('client.upload', ['token' => $this->invitation->token]),
                 'expiresAt' => $this->invitation->expires_at->format('d/m/Y à H:i'),
+                'firmName' => $this->declaration->workspace?->name,
             ]
         );
     }