feat: 🚀 Evolve to Stateful MCP Architecture with Context Injection Middleware

Major architectural overhaul to decouple Agent Logic (Service) from Tool Execution (Server) using the Model Context Protocol (MCP).

Key Highlights:
- **Micro-Architecture**: Migrated local toolkits to a standalone `FastMCP` server process (`mcp_server_lifeflow.py`).
- **Context Engineering**: Implemented an AOP-style interceptor using Python `ContextVars`. This automatically injects `session_id` and `api_key` into MCP tool calls, keeping Agent prompts clean and reducing token usage.
- **Multi-Tenant Safety**: Achieved strict session isolation. User-provided API keys dynamically override system environment variables via the injection layer.
- **Runtime Metaprogramming**: Solved Agno/Phidata internal naming conflicts (`_` prefix) by dynamically patching tool entrypoints at startup.
- **Exclusive Channels**: Configured dedicated MCP pipes for each Agent (`Scout`, `Navigator`, etc.) to prevent tool hallucination.

This commit satisfies all requirements for Hackathon Track 2: MCP in Action.

src/infra/client_context.py

@@ -0,0 +1,5 @@
+# src/infra/client_context.py
+from contextvars import ContextVar
+
+# 建立一個 Async 任務隔離的變數，預設為 None
+client_session_ctx = ContextVar("client_session_id", default=None)