chore: add config-overrides.json to ignore files and docker volume

- Add config-overrides.json to .gitignore (user-specific runtime config)
- Add config-overrides.json to .dockerignore (not needed in image)
- Mount config-overrides.json as volume in docker-compose.yml

This enables persistent configuration overrides in containerized
deployments without rebuilding the image.

.dockerignore

@@ -7,3 +7,4 @@ frontend/node_modules/
 
 # 忽略 kubernetes.yaml
 kubernetes.yaml
+config-overrides.json

.gitignore

@@ -2,3 +2,4 @@ node_modules/
 dist/
 .env
 kubernetes.yaml
+config-overrides.json

docker-compose.yml

@@ -10,6 +10,8 @@ services:
     restart: unless-stopped
     ports:
       - "3000:3000"
+    volumes:
+      - ./config-overrides.json:/app/config-overrides.json
     env_file:
       - .env
     healthcheck: