Harden UIA control collection

[rodion-m]

Summary

• respect depth=1 in the UIA backend by using TreeScope_Children instead of always walking all descendants
• make UIA control collection best-effort so COM/UIA failures return partial or empty results instead of failing the MCP tool
• document the new optional depth and best_effort parameters for control collection tools

Validation

• python -m py_compile ufo\automator\ui_control\inspector.py ufo\client\mcp\local_servers\ui_mcp_server.py
• git diff --check

[rodion-m]

@microsoft-github-policy-service agree