Refactor backend to support interface-definition driven model resources

- Introduce a new model structure for managing interface definitions and model resources, enhancing the backend's capability to handle various service integrations.
- Update the Makefile to reflect changes in database seeding and resource management commands.
- Remove the deprecated credentials management routes and replace them with a unified model registry API.
- Modify existing routes and schemas to align with the new model structure, ensuring seamless integration with the frontend.
- Enhance database seeding scripts to populate new model resources and their configurations.
- Update README documentation to reflect the new architecture and usage instructions for model resources and interface definitions.

backend/app.py

@@ -5,7 +5,8 @@
 路由分组(对齐 dograh 的 routes/ 结构):
   /health              健康检查
   /api/assistants      助手 CRUD
-  /api/credentials     模型凭证 CRUD(key 打码)
+  /api/interface-definitions 接口定义
+  /api/model-resources 模型资源 CRUD
   /ws/voice            WebRTC 输出(浏览器)
   /ws/stream           WS 输出(裸音频流)
 """
@@ -20,9 +21,9 @@ from fastapi.middleware.cors import CORSMiddleware
 
 from routes import (
     assistants,
-    credentials,
     health,
     knowledge_bases,
+    model_registry,
     voice_webrtc,
     voice_ws,
 )
@@ -46,8 +47,8 @@ app.add_middleware(
 
 app.include_router(health.router)
 app.include_router(assistants.router)
-app.include_router(credentials.router)
 app.include_router(knowledge_bases.router)
+app.include_router(model_registry.router)
 app.include_router(voice_webrtc.router)
 app.include_router(voice_ws.router)