feat(D): Phase D — Undo/Restore komplett implementiert

- D-GEN: RestoreRegistry mit RestoreConfig (model_class, restore_permission, excluded_fields, special_handler)
- D-HOOK: history_hooks.py mit register_history_hooks() für after_create/update/delete
- D-CORE: Company create+update record_history in companies.py
- D-PLUG: Task/Calendar/DMS record_history in services/routes
- D-SOFT: Alle registrierten Entitäten haben deleted_at + un-delete via Registry
- D-MAIL: Mail special_handler (IMAP Trash-Move, Folder-Verify) + record_history in delete/move
- D-TRASH: GET /entity-history/trash (filterbar, paginiert) + Frontend Trash.tsx
- D-TOAST: UndoToast.tsx (5s Auto-Dismiss, useUndoToast Hook)
- D-HIST-UI: HistoryPanel.tsx (Timeline, Diff-View, Restore-Button)
- D-BULK: POST /entity-history/bulk-restore mit partial_success Semantik
- D-RET: POST /entity-history/retention/archive (GDPR hard-delete >90 Tage)
- D-TEST: 26 Tests in test_restore_registry.py, alle grün
- D-DOC: test-strategy.md + security_kernel.md aktualisiert

Backend: 10 Dateien, Frontend: 7 Dateien, Tests: 1 Datei, Docs: 3 Dateien
26/26 Tests passed, TSC 0 errors, App import 492 routes

frontend/src/i18n/locales/de.json

@@ -907,7 +907,39 @@
     "restoreError": "Wiederherstellung fehlgeschlagen",
     "empty": "Keine Änderungshistorie vorhanden",
     "changes": "Änderungen",
-    "fieldsChanged": "Felder geändert"
+    "fieldsChanged": "Felder geändert",
+    "actionCreate": "Erstellt",
+    "actionUpdate": "Aktualisiert",
+    "actionDelete": "Gelöscht"
+  },
+  "trash": {
+    "title": "Papierkorb",
+    "allTypes": "Alle Typen",
+    "filterType": "Entity-Typ",
+    "entityType": "Typ",
+    "name": "Name",
+    "deletedAt": "Gelöscht am",
+    "actions": "Aktionen",
+    "restore": "Wiederherstellen",
+    "restored": "Wiederhergestellt",
+    "restoreError": "Wiederherstellung fehlgeschlagen",
+    "bulkRestore": "Ausgewählte wiederherstellen",
+    "bulkRestored": "{{count}} Einträge wiederhergestellt",
+    "bulkPartial": "{{succeeded}} wiederhergestellt, {{failed}} fehlgeschlagen",
+    "bulkRestoreError": "Massen-Wiederherstellung fehlgeschlagen",
+    "empty": "Papierkorb ist leer",
+    "selectAll": "Alle auswählen",
+    "selectItem": "Eintrag auswählen",
+    "types": {
+      "contact": "Kontakt",
+      "task": "Aufgabe",
+      "calendar_entry": "Kalendereintrag",
+      "dms_file": "Datei",
+      "mail": "E-Mail"
+    }
+  },
+  "undoToast": {
+    "undo": "Undo"
   },
   "userPreferences": {
     "title": "Benutzereinstellungen",

frontend/src/i18n/locales/en.json

@@ -907,7 +907,39 @@
     "restoreError": "Restore failed",
     "empty": "No change history available",
     "changes": "Changes",
-    "fieldsChanged": "fields changed"
+    "fieldsChanged": "fields changed",
+    "actionCreate": "Created",
+    "actionUpdate": "Updated",
+    "actionDelete": "Deleted"
+  },
+  "trash": {
+    "title": "Trash",
+    "allTypes": "All types",
+    "filterType": "Entity type",
+    "entityType": "Type",
+    "name": "Name",
+    "deletedAt": "Deleted at",
+    "actions": "Actions",
+    "restore": "Restore",
+    "restored": "Restored",
+    "restoreError": "Restore failed",
+    "bulkRestore": "Restore selected",
+    "bulkRestored": "{{count}} entries restored",
+    "bulkPartial": "{{succeeded}} restored, {{failed}} failed",
+    "bulkRestoreError": "Bulk restore failed",
+    "empty": "Trash is empty",
+    "selectAll": "Select all",
+    "selectItem": "Select item",
+    "types": {
+      "contact": "Contact",
+      "task": "Task",
+      "calendar_entry": "Calendar entry",
+      "dms_file": "File",
+      "mail": "Email"
+    }
+  },
+  "undoToast": {
+    "undo": "Undo"
   },
   "userPreferences": {
     "title": "User Preferences",