Stand: SMTP-Test, Admin-Mail-Tab, Notifiable-Fix, Lazy-Quill

- Fix: Notifiable-Trait zum User-Model hinzugefuegt (behebt notify()-500er)
- Installer: SMTP-Verbindungstest mit EsmtpTransport + Ueberspringen-Link
- Admin: Neuer E-Mail-Tab mit SMTP-Konfiguration + Verbindungstest
- Admin: Lazy Quill-Initialisierung (nur sichtbare Locale wird geladen)
- Uebersetzungen: 17 neue Mail-Keys in allen 6 Sprachen

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vendor/laravel/sail/stubs/mysql.stub

@@ -0,0 +1,21 @@
+mysql:
+    image: 'mysql:8.4'
+    ports:
+        - '${FORWARD_DB_PORT:-3306}:3306'
+    environment:
+        MYSQL_ROOT_PASSWORD: '${DB_PASSWORD}'
+        MYSQL_ROOT_HOST: "%"
+        MYSQL_DATABASE: '${DB_DATABASE}'
+        MYSQL_USER: '${DB_USERNAME}'
+        MYSQL_PASSWORD: '${DB_PASSWORD}'
+        MYSQL_ALLOW_EMPTY_PASSWORD: 1
+        MYSQL_EXTRA_OPTIONS: '${MYSQL_EXTRA_OPTIONS:-}'
+    volumes:
+        - 'sail-mysql:/var/lib/mysql'
+        - './vendor/laravel/sail/database/mysql/create-testing-database.sh:/docker-entrypoint-initdb.d/10-create-testing-database.sh'
+    networks:
+        - sail
+    healthcheck:
+        test: ["CMD", "mysqladmin", "ping", "-p${DB_PASSWORD}"]
+        retries: 3
+        timeout: 5s