fix: resolve permission toggle persistence, nudge terminology, and bulk action bugs (Bugs #2-5)

- Fix togglePermission() to always include all permission keys with false defaults
- Add migration to backfill null/empty Manager permissions with config defaults
- Rename nudge UI text from "Relance" to "Notification"/"Notifier" across 8 files
- Fix select-all checkbox and show checkboxes on all declaration rows
- Remove en_attente_client status restriction from BulkNotificationController

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

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

@@ -78,7 +78,7 @@ development_status:
   3-2-one-click-nudge-system: done
   3-3-notification-center-and-bell: done
   3-4-bulk-client-notification-scheduling: done
-  3-5-email-notification-enhancement-for-key-events: review
+  3-5-email-notification-enhancement-for-key-events: done
   epic-3-retrospective: optional
 
   # Epic 4: Bulk Operations, Search & Advanced Filtering