Backport upstream fixes: qq/cron/web/tools/mcp robustness

[bitifirefly]

Summary

• keep QQ channel start running as a long-lived task and close client cleanly on stop
• reload cron store on each timer tick so external updates are picked up
• resolve web search API key at call time instead of import time
• improve edit_file mismatch diagnostics for easier debugging
• add MCP tool-call timeout guard and explicit HTTP transport client with timeout=None

Testing

• ruff check opencane/channels/qq.py tests/test_qq_channel.py opencane/cron/service.py tests/test_cron_service.py opencane/agent/tools/web.py tests/test_web_search_tool.py opencane/agent/tools/filesystem.py tests/test_filesystem_tools_workspace.py opencane/agent/tools/mcp.py tests/test_mcp_tool.py
• pytest -q tests/test_qq_channel.py tests/test_cron_service.py tests/test_web_search_tool.py tests/test_filesystem_tools_workspace.py tests/test_mcp_tool.py
• pytest -q (426 passed)