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>

database/migrations/2026_03_27_000001_backfill_manager_permissions.php

@@ -0,0 +1,34 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Support\Facades\DB;
+
+return new class extends Migration
+{
+    /**
+     * Backfill Manager workspace_user rows that have null or empty permissions
+     * with the defaults from config('permissions.defaults.manager').
+     */
+    public function up(): void
+    {
+        $defaults = json_encode(config('permissions.defaults.manager'));
+
+        DB::table('workspace_user')
+            ->where('role', 'manager')
+            ->where(function ($query) {
+                $query->whereNull('permissions')
+                    ->orWhere('permissions', '[]')
+                    ->orWhere('permissions', 'null')
+                    ->orWhere('permissions', '');
+            })
+            ->update(['permissions' => $defaults]);
+    }
+
+    /**
+     * Reverse the migration (no-op — we cannot know original values).
+     */
+    public function down(): void
+    {
+        // Cannot reverse: original null/empty values are indistinguishable
+    }
+};