chore: add prod deploy files — migration service + env example

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

docker-compose.prod.yml

@@ -1,4 +1,16 @@
 services:
+  migrate:
+    image: git.vicolab.de/schalli/tessera-ctl/api:latest
+    command: sh -c "cd /app && node_modules/.bin/prisma migrate deploy --schema apps/api/prisma/schema.prisma"
+    environment:
+      DATABASE_URL: ${DATABASE_URL}
+    networks:
+      - data-net
+    depends_on:
+      db:
+        condition: service_healthy
+    restart: "no"
+
   web:
     image: git.vicolab.de/schalli/tessera-ctl/web:latest
     restart: unless-stopped
@@ -27,6 +39,8 @@ services:
     depends_on:
       db:
         condition: service_healthy
+      migrate:
+        condition: service_completed_successfully
     environment:
       DATABASE_URL: ${DATABASE_URL}
       JWT_SECRET: ${JWT_SECRET}