fix: preserve static MCP meta in converted function tools

[seratch]

This pull request fixes converted MCP function tools dropping static _meta at execution time.

MCPUtil.to_function_tool() previously converted MCP tools into FunctionTool instances without carrying static request metadata through to invoke_mcp_tool(). That meant MCP servers relying on _meta for request-scoped hints such as auth, locale, or session data could silently lose that information when tools were invoked through the SDK's function-tool path.

This change keeps the fix narrow to the MCP conversion layer. It extracts static MCP metadata from the MCP tool object, including the current mcp.types.Tool Pydantic shape, and binds that metadata into invoke_mcp_tool() so the existing merge logic with tool_meta_resolver remains the single execution path.

The pull request also adds regression coverage to verify that:

• static MCP metadata survives to_function_tool() conversion and reaches server.call_tool(...)
• static MCP metadata still merges correctly with resolver-produced metadata and preserves existing precedence rules