feat(tool): 推断 MCP session_affinity 以支持 MCP_REMOTE proxy 模式

[117503445]

Signed-off-by: 黑曜 haotian.qht@alibaba-inc.com

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Pull request overview

Adds inference of MCP session_affinity from protocol_spec for the MCP_REMOTE + proxy_enabled scenario when mcp_config.session_affinity is empty, so the proxy mode can correctly route to streamable-http upstream MCP servers.

Changes:

• Add _infer_protocol_spec_mcp_session_affinity helper that parses protocol_spec.mcpServers[*].transportType to derive MCP_STREAMABLE / MCP_SSE.
• Update _get_mcp_endpoint to call the inference when session_affinity is empty under MCP_REMOTE proxy mode, falling back to MCP_SSE.
• Add unit tests covering inference for missing and empty session_affinity.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
agentrun/tool/tool.py	Adds inference helper and integrates it into _get_mcp_endpoint.
agentrun/tool/__tool_async_template.py	Mirrors the same change in the async template (codegen source).
tests/unittests/tool/test_tool.py	Adds two test cases covering proxy-mode streamable inference.

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