feat: add Mietvertrag workflow and template management in n8n, including email notifications and document handling

Co-authored-by: Copilot <copilot@github.com>

docker-compose.yml

@@ -217,6 +217,7 @@ services:
       - /mnt/user/appdata/mc-cars/supabase/migrations/07-sales-orders.sql:/sql/07-sales-orders.sql:ro
       - /mnt/user/appdata/mc-cars/supabase/migrations/08-backend-pricing-and-security.sql:/sql/08-backend-pricing-and-security.sql:ro
       - /mnt/user/appdata/mc-cars/supabase/migrations/09-site-settings.sql:/sql/09-site-settings.sql:ro
+      - /mnt/user/appdata/mc-cars/supabase/migrations/10-mietvertrag-workflow.sql:/sql/10-mietvertrag-workflow.sql:ro
     entrypoint: ["sh","-c"]
     command:
       - |
@@ -242,6 +243,7 @@ services:
         psql "postgresql://postgres:$$PGPASSWORD@db:5432/postgres" -v ON_ERROR_STOP=1 -f /sql/07-sales-orders.sql
         psql "postgresql://postgres:$$PGPASSWORD@db:5432/postgres" -v ON_ERROR_STOP=1 -f /sql/08-backend-pricing-and-security.sql
         psql "postgresql://postgres:$$PGPASSWORD@db:5432/postgres" -v ON_ERROR_STOP=1 -f /sql/09-site-settings.sql
+        psql "postgresql://postgres:$$PGPASSWORD@db:5432/postgres" -v ON_ERROR_STOP=1 -f /sql/10-mietvertrag-workflow.sql
         echo "post-init done."
     restart: "no"
     networks: [mccars]
@@ -413,3 +415,19 @@ services:
       - "55590:5678"
     networks: [mccars]
     logging: { driver: json-file, options: { max-size: "10m", max-file: "3" } }
+
+  # -------------------------------------------------------------------------
+  # Gotenberg - headless document converter (DOCX → PDF)
+  # Used by n8n to generate Mietvertrag PDFs from DOCX templates.
+  # -------------------------------------------------------------------------
+  gotenberg:
+    image: gotenberg/gotenberg:8
+    container_name: mccars-gotenberg
+    restart: unless-stopped
+    command:
+      - "gotenberg"
+      - "--api-port=3000"
+      - "--api-timeout=60s"
+      - "--libreoffice-restart-after=10"
+    networks: [mccars]
+    logging: { driver: json-file, options: { max-size: "10m", max-file: "3" } }