Finish shared-desktop UIA fallbacks

[coneilen]

Summary

Finishes the shared-desktop UIA stabilization by making verified native menu
and modal actions deterministic when global input is accepted by Windows but
does not reach the owned GraphCode target.

Changes

• drain queued edit input before restoring exact fallback text
• synchronize nested menu hover and select the exact verified HMENU item
• fall back to the exact verified owner command only after bounded native input
  and modal waits fail
• record every menu, submenu, modal, and text fallback in retained evidence

Test plan

RED: pwsh -NoProfile -File Tools\windows\Tests\ValidationRunner.Tests.ps1 -> RED: UIA live gate lacked synchronized submenu and modal command fallbacks
GREEN: pwsh -NoProfile -File Tools\windows\Tests\ValidationRunner.Tests.ps1 -> PASS; 380 multi-project protocol contracts executed
REGRESSION: pwsh -NoProfile -File Tools\windows\validate.ps1 -Task windows-shell -ShellPart integration -SkipTrayLive -ShellValidationRoot C:\v5 -SwiftExecutable $env:GRAPHCODE_SWIFT633 -> exit 0; shell smoke, daemon handoff, tray contracts, full native UIA, process cleanup, and profile isolation passed

Checklist

• I have read the Contributing Guidelines
• I have signed off my commits (git commit -s) per the DCO
• Tests pass locally (make test)
• Code follows the existing style (make check)
• I added the test/contract before the implementation and observed the intended RED failure

make test and make check are macOS entry points and were not run on this
Windows host; the Windows-specific commands above are the applicable repository
validation.