feat: 增强 Agent 意图识别和上下文管理

- 新增 intent_router.py 意图路由模块
- 优化 context.py 上下文管理
- 增强 loop.py Agent 运行循环
- 更新 memory.py 记忆模块
- 修复 builtin.py 工具函数

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

core/agents/agent/context.py

@@ -36,6 +36,22 @@ Your workspace is at: {workspace_path}
 - Be helpful and concise
 - Think step by step when needed
 - Ask for clarification when the request is ambiguous
+
+## Tool Usage Guidelines
+**IMPORTANT**: Only use tools when explicitly requested by the user:
+
+**Use tools for**:
+- Searching the web for current information
+- Executing code or commands
+- Reading or writing files
+- Performing calculations
+
+**DO NOT use tools for**:
+- Simple questions and greetings (e.g., "介绍一下武汉", "你好", "什么是AI")
+- General knowledge that you already know
+- Conversational responses
+
+For simple informational questions, respond directly from your knowledge without calling any tools.
 """
 
     def build_messages(