Add Docker packaging and Gitea Actions CI/CD pipeline.

Containerize the app for local and production deploys, and publish images
to the Gitea container registry on main pushes and version tags.

Co-authored-by: Cursor <cursoragent@cursor.com>

docker-compose.yml

@@ -0,0 +1,23 @@
+services:
+  app:
+    build: .
+    ports:
+      - "${PORT:-8099}:8099"
+    env_file:
+      - backend/.env
+    environment:
+      # Override in backend/.env for production (email links, etc.)
+      APP_BASE_URL: ${APP_BASE_URL:-http://localhost:8099}
+    volumes:
+      - uploads:/app/backend/uploads
+      - outputs:/app/backend/outputs
+      - llm_cache:/app/backend/.llm_cache
+    extra_hosts:
+      # Reach a vLLM box on the Docker host (hybrid text backend)
+      - "host.docker.internal:host-gateway"
+    restart: unless-stopped
+
+volumes:
+  uploads:
+  outputs:
+  llm_cache: