feat(deploy): fix docker deployment and add backend i18n

- Docker Deployment Fixes:
  - Switch base images to docker.m.daocloud.io to resolve registry 401 errors
  - Add Postgres and Redis services to docker-compose.traefik.yml
  - Fix frontend build: replace missing icons (Globe->Location, Chart->TrendCharts)
  - Fix frontend build: resolve pnpm CI/TTY issues and frozen lockfile errors
  - Add missing backend dependencies (sqlalchemy, psycopg2, redis-py, celery, docker-py) in pixi.toml
  - Ensure database tables are created on startup (lifespan event)

- Backend Internationalization (i18n):
  - Add backend/app/core/i18n.py for locale handling
  - Update API endpoints (jobs, tasks, uploads, results) to return localized messages
  - Support 'Accept-Language' header (en/zh)

- Documentation:
  - Update DOCKER_DEPLOYMENT.md with new architecture and troubleshooting
  - Update AGENTS.md with latest stack details and deployment steps
  - Update @fix_plan.md status

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

docker/compose/docker-compose.traefik.yml

@@ -3,6 +3,26 @@
 # The container exposes port 8000 where FastAPI serves both API and frontend
 
 services:
+  postgres:
+    image: docker.m.daocloud.io/library/postgres:15-alpine
+    container_name: bttoxin-postgres
+    restart: unless-stopped
+    environment:
+      - POSTGRES_USER=postgres
+      - POSTGRES_PASSWORD=password
+      - POSTGRES_DB=bttoxin
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    networks:
+      - traefik-network
+
+  redis:
+    image: docker.m.daocloud.io/library/redis:7-alpine
+    container_name: bttoxin-redis
+    restart: unless-stopped
+    networks:
+      - traefik-network
+
   bttoxin:
     build:
       context: ../..
@@ -13,8 +33,14 @@ services:
       - ../../jobs:/app/jobs
     environment:
       - JOBS_DIR=/app/jobs
-      # No need for ROOT_PATH since Traefik handles the routing
+      - DATABASE_URL=postgresql://postgres:password@postgres:5432/bttoxin
+      - REDIS_URL=redis://redis:6379/0
+      - CELERY_BROKER_URL=redis://redis:6379/0
+      - CELERY_RESULT_BACKEND=redis://redis:6379/0
     restart: unless-stopped
+    depends_on:
+      - postgres
+      - redis
     networks:
       - traefik-network
     labels:
@@ -44,6 +70,9 @@ networks:
     # Create this network first: docker network create traefik-network
     # Or set external: false to let docker-compose create it
 
+volumes:
+  postgres_data:
+
 # Example Traefik configuration (traefik.yml):
 #
 # services: