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/routes/knowledge_bases.py

@@ -1,12 +1,12 @@
 """知识库 CRUD。前端助手编辑页的"知识库"下拉对接这里。
 
-KB 自身引用一个 Embedding 凭证(embeddingCredentialId)。被助手引用时禁止删除
+KB 自身引用一个 Embedding 模型资源。被助手引用时禁止删除
 (DB 层 ON DELETE RESTRICT),这里把外键冲突翻译成 409。
 """
 
 import uuid
 
-from db.models import KnowledgeBase
+from db.models import KnowledgeBase, ModelResource
 from db.session import get_session
 from fastapi import APIRouter, Depends, HTTPException
 from schemas import KnowledgeBaseOut, KnowledgeBaseUpsert
@@ -17,12 +17,22 @@ from sqlalchemy.ext.asyncio import AsyncSession
 router = APIRouter(prefix="/api/knowledge-bases", tags=["knowledge-bases"])
 
 
+async def _validate_embedding_resource(
+    session: AsyncSession, resource_id: str | None
+) -> None:
+    if not resource_id:
+        return
+    resource = await session.get(ModelResource, resource_id)
+    if not resource or resource.capability != "Embedding":
+        raise HTTPException(400, "知识库必须引用 Embedding 模型资源")
+
+
 def _to_out(kb: KnowledgeBase) -> KnowledgeBaseOut:
     return KnowledgeBaseOut(
         id=kb.id,
         name=kb.name,
         description=kb.description,
-        embedding_credential_id=kb.embedding_credential_id,
+        embedding_model_resource_id=kb.embedding_model_resource_id,
         status=kb.status,
         updated_at=kb.updated_at.isoformat() if kb.updated_at else None,
     )
@@ -40,6 +50,7 @@ async def list_knowledge_bases(session: AsyncSession = Depends(get_session)):
 async def create_knowledge_base(
     body: KnowledgeBaseUpsert, session: AsyncSession = Depends(get_session)
 ):
+    await _validate_embedding_resource(session, body.embedding_model_resource_id)
     kb = KnowledgeBase(id=f"kb_{uuid.uuid4().hex[:12]}", **body.model_dump())
     session.add(kb)
     await session.commit()
@@ -66,6 +77,7 @@ async def update_knowledge_base(
     kb = await session.get(KnowledgeBase, kb_id)
     if not kb:
         raise HTTPException(404, "知识库不存在")
+    await _validate_embedding_resource(session, body.embedding_model_resource_id)
     for k, v in body.model_dump().items():
         setattr(kb, k, v)
     await session.commit()