feat(ECR-023): AICoreConfig KnowledgeSource 只读并 Closed

运营可观测知识源目录（knowledge_sources + admin /ai），不含 Chunk/Embedding。

Co-authored-by: Cursor <cursoragent@cursor.com>

proto/openapi.yaml

@@ -555,6 +555,34 @@ paths:
         '404':
           description: Not found
 
+  /api/v1/admin/ai/knowledge-sources:
+    get:
+      tags: [admin]
+      summary: List KnowledgeSource catalog
+      description: Requires admin.ai_config.read
+      responses:
+        '200':
+          description: OK
+        '401':
+          description: Unauthorized
+        '403':
+          description: Forbidden
+
+  /api/v1/admin/ai/knowledge-sources/{id}:
+    get:
+      tags: [admin]
+      summary: Get KnowledgeSource
+      parameters:
+        - in: path
+          name: id
+          required: true
+          schema: { type: string, format: uuid }
+      responses:
+        '200':
+          description: OK
+        '404':
+          description: Not found
+
   /api/v1/admin/crisis/policies:
     get:
       tags: [admin]