feat(engine): 添加MCP连接管理和工具集成功能

- 集成MCP连接管理器，支持MCP服务器连接
- 添加多种内置工具：ClarifyTool、CronTool、DelegateTool、ExecuteCodeTool、
  PatchFileTool、ProcessTool、SendMessageTool、SpawnTool、TerminalTool、
  TodoTool、WebFetchTool、WebSearchTool、WriteFileTool等
- 实现工具注册和装配功能
- 添加技能选择上下文参数
- 支持思考模式控制参数thinking_enabled

feat(coordinator): 重构任务执行计划器参数命名

- 将learning_candidate_enabled重命名为allow_candidate_generation
- 更新TeamGraphScheduler中的参数传递
- 修改LocalAgentRunner中的相关参数处理
- 更新README文档中的相应描述

refactor(context): 标准化工具调用参数格式

- 添加_json导入用于参数序列化
- 实现_provider_tool_calls方法标准化OpenAI兼容的工具调用载荷
- 修复工具调用中参数非字符串类型的序列化问题

refactor(session): 优化消息历史记录过滤逻辑

- 修改get_messages_as_conversation为基于运行状态过滤消息
- 排除未完成、失败或错误结束的运行记录
- 改进对话历史的可见性控制机制

fix(store): 修复FTS索引重建逻辑

- 添加异常处理防止FTS索引创建失败
- 实现_rebuild_fts_index方法重新构建全文搜索索引
- 优化索引触发器和表的维护流程

app-instance/backend/beaver/integrations/authz/client.py

@@ -0,0 +1,50 @@
+"""Small async client for the internal AuthZ service."""
+
+from __future__ import annotations
+
+from typing import Any
+
+import httpx
+
+
+class AuthzClient:
+    def __init__(self, base_url: str, timeout_seconds: int = 10) -> None:
+        self.base_url = base_url.rstrip("/")
+        self.timeout_seconds = timeout_seconds
+
+    async def _request(self, method: str, path: str, *, json_body: dict[str, Any] | None = None) -> Any:
+        async with httpx.AsyncClient(
+            timeout=self.timeout_seconds,
+            follow_redirects=True,
+            trust_env=False,
+        ) as client:
+            response = await client.request(method, f"{self.base_url}{path}", json=json_body)
+        response.raise_for_status()
+        if not response.content:
+            return None
+        return response.json()
+
+    async def issue_token(
+        self,
+        *,
+        client_id: str,
+        client_secret: str,
+        audience: str,
+        scopes: list[str],
+    ) -> dict[str, Any]:
+        data = await self._request(
+            "POST",
+            "/oauth/token",
+            json_body={
+                "grant_type": "client_credentials",
+                "client_id": client_id,
+                "client_secret": client_secret,
+                "aud": audience,
+                "scopes": list(scopes),
+            },
+        )
+        return data if isinstance(data, dict) else {}
+
+    async def get_permissions(self, backend_id: str) -> dict[str, Any]:
+        data = await self._request("GET", f"/backends/{backend_id}/permissions")
+        return data if isinstance(data, dict) else {}