feat: notification preferences system with plugin registry

- Add NotificationType and NotificationPreference models
- Add get_notification_types() to BasePlugin for plugin registration
- Add sync_notification_types() to PluginRegistry
- Update create_notification() to check user preferences (returns Notification|None)
- Add API endpoints: GET /types, GET /preferences, PATCH /preferences/{type_key}
- Add NotificationPreferenceUpdate schema
- Mail plugin registers 10 notification types with metadata
- Add Alembic migration 0017 for new tables + seed data
- Frontend: SettingsNotifications page with toggle switches
- Frontend: Settings tab, route, hooks for notification preferences
- i18n: notification settings keys (de/en)

app/plugins/builtins/mail/plugin.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import asyncio
 import logging
+from typing import Any
 
 from app.plugins.base import BasePlugin
 from app.plugins.manifest import PluginManifest, PluginRouteDef
@@ -59,6 +60,21 @@ class MailPlugin(BasePlugin):
             self._auto_sync_task = asyncio.create_task(_auto_sync_loop())
             logger.info("Mail plugin: auto-sync background task started")
 
+    def get_notification_types(self) -> list[dict[str, Any]]:
+        """Return the notification types this mail plugin registers."""
+        return [
+            {"type_key": "mail_new", "category": "mail", "label": "Neue E-Mail empfangen", "description": "Benachrichtigung bei neuen E-Mails", "is_enabled_by_default": True},
+            {"type_key": "mail_error", "category": "mail", "label": "IMAP-Verbindungsfehler", "description": "Fehler bei der Verbindung zum Mailserver", "is_enabled_by_default": True},
+            {"type_key": "mail_auth", "category": "mail", "label": "IMAP-Login-Fehler", "description": "Anmeldung am Mailserver fehlgeschlagen", "is_enabled_by_default": True},
+            {"type_key": "mail_quota", "category": "mail", "label": "Postfach fast voll", "description": "Warnung bei hohem Postfach-Füllstand", "is_enabled_by_default": True},
+            {"type_key": "mail_sync_error", "category": "mail", "label": "Sync-Fehler", "description": "Synchronisierung fehlgeschlagen", "is_enabled_by_default": True},
+            {"type_key": "mail_sent", "category": "mail", "label": "E-Mail gesendet", "description": "Bestätigung beim Senden einer E-Mail", "is_enabled_by_default": False},
+            {"type_key": "mail_send_error", "category": "mail", "label": "SMTP-Sendefehler", "description": "E-Mail konnte nicht gesendet werden", "is_enabled_by_default": True},
+            {"type_key": "mail_draft", "category": "mail", "label": "Entwurf gespeichert", "description": "Bestätigung beim Speichern eines Entwurfs", "is_enabled_by_default": False},
+            {"type_key": "mail_account", "category": "mail", "label": "Account deaktiviert", "description": "Warnung bei deaktiviertem Mail-Account", "is_enabled_by_default": True},
+            {"type_key": "mail_folder", "category": "mail", "label": "Ordner erstellt/gelöscht", "description": "Bestätigung bei Ordner-Operationen", "is_enabled_by_default": False},
+        ]
+
     async def on_deactivate(
         self, db, service_container, event_bus
     ) -> None: