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/pgsql.stub

@@ -0,0 +1,18 @@
+pgsql:
+    image: 'postgres:18-alpine'
+    ports:
+        - '${FORWARD_DB_PORT:-5432}:5432'
+    environment:
+        PGPASSWORD: '${DB_PASSWORD:-secret}'
+        POSTGRES_DB: '${DB_DATABASE}'
+        POSTGRES_USER: '${DB_USERNAME}'
+        POSTGRES_PASSWORD: '${DB_PASSWORD:-secret}'
+    volumes:
+        - 'sail-pgsql:/var/lib/postgresql'
+        - './vendor/laravel/sail/database/pgsql/create-testing-database.sql:/docker-entrypoint-initdb.d/10-create-testing-database.sql'
+    networks:
+        - sail
+    healthcheck:
+        test: ["CMD", "pg_isready", "-q", "-d", "${DB_DATABASE}", "-U", "${DB_USERNAME}"]
+        retries: 3
+        timeout: 5s