refactor: split backend into standalone server project

Remove embedded frontend and workflow editor assets, add standalone API deployment configuration, and retain the current backend service updates.

config/config.example.yaml

@@ -2,20 +2,23 @@ language: zh-CN
 
 server:
   port: 8083
+  # Public address of the independently deployed frontend. Login callbacks redirect here.
+  frontendUrl: http://127.0.0.1:3000
   cors:
     # Browser CORS allowlist. In production, replace this with the actual frontend or embedded-site domains, such as https://support.example.com.
     # Leave it empty to reject cross-origin browser requests. Same-origin and non-browser calls are still supported.
     allowedOrigins:
-      - http://127.0.0.1:8083
-      - http://localhost:8083
+      - http://127.0.0.1:3000
+      - http://localhost:3000
 
 db:
-  # Database driver. Supported values: sqlite, mysql.
+  # Database driver. Supported values: sqlite, mysql, postgres (postgresql is also accepted).
   type: sqlite
   # Database connection string.
   # SQLite example: file:./data/app.db?_busy_timeout=5000
   # MySQL example: user:password@tcp(127.0.0.1:3306)/cs_ai_agent_db?charset=utf8mb4&parseTime=True&multiStatements=true&loc=Local
   # For MySQL, keep parseTime=True so datetime fields are scanned into Go time values correctly.
+  # PostgreSQL example: host=127.0.0.1 user=cs_ai_agent password=change-me dbname=cs_ai_agent port=5432 sslmode=disable TimeZone=Asia/Shanghai
   dsn: file:./data/app.db?_busy_timeout=5000
   # Maximum number of idle connections kept in the pool. Values <= 0 use the database/sql default.
   maxIdleConns: 5
@@ -61,7 +64,7 @@ storage:
     root: data/storage
     # Public URL prefix used when returning local file URLs. The server must expose this path as static files.
     # Example: storage key "images/a.png" becomes "/storage/images/a.png".
-    baseUrl: /storage
+    baseUrl: http://127.0.0.1:8083/storage
   oss:
     # Aliyun OSS endpoint. Both "oss-cn-hangzhou.aliyuncs.com" and "https://oss-cn-hangzhou.aliyuncs.com" are accepted.
     endpoint: ""