fix(file-locksmith): isolate handle enumeration

[Clint Rutkas (crutkas)]

Summary of the Pull Request

Fixes File Locksmith UI access violations and hangs by moving blockable native handle enumeration into a disposable FileLocksmithCLI.exe worker process. The UI communicates through BOM-free UTF-8 JSON over redirected stdin/stdout, enforces a 30-second timeout, and surfaces timeout or worker failures explicitly instead of showing “No results.”

This supersedes the incomplete mitigation in draft PR #49502 and addresses the crash scenarios reported in #45158 and #47200. It is intentionally separate from the File Locksmith context-menu HANG_QUIESCE lifecycle work and does not modify that code.

PR Checklist

• Closes: File Locksmith Crash #45158
• Closes: FileLocksmith runs for 5 sec and then crashes #47200
• Communication: I've discussed this with core contributors already. If the work hasn't been agreed, this work might be rejected
• Tests: Added/updated and all pass
• Localization: All end-user-facing strings can be localized
• Dev docs: Added/updated

Detailed Description of the Pull Request / Additional comments

• Removes the detached enumeration thread and unsafe TerminateThread recovery from src/modules/FileLocksmith/FileLocksmithLibInterop/NtdllExtensions.cpp.
• Adds hidden FileLocksmithCLI.exe --worker-json mode. Selected paths are sent in UTF-8 JSON over stdin, never command-line arguments or logs; results return as JSON over stdout.
• Assigns each worker to a JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE job, terminates the worker process tree on timeout/cancellation, and waits for cleanup. Elevation restart cancels and awaits the active query before exiting.
• Preserves elevated/non-elevated visibility because the worker inherits the UI token and debug privilege state. Reload and End Task behavior remain unchanged.
• Adds localized timeout/failure InfoBar states in src/modules/FileLocksmith/FileLocksmithUI/FileLocksmithXAML/Views/MainPage.xaml and Strings/en-us/Resources.resw.
• Retains PR [File Locksmith] Fix Interop access-violation crashes from TerminateThread hang recovery #49502's independently correct UNICODE_STRING and OpenProcess null guards. It does not use the four GrantedAccess heuristics from [File Locksmith] Fix Interop access-violation crashes from TerminateThread hang recovery #49502 because those masks are incomplete and would introduce false-negative lock detection.
• Logs only stage, duration, status/exit code, input count, and result count; selected file paths are not logged.
• Documents the 30-second finite timeout in doc/devdocs/modules/filelocksmith.md.

Known risk: A legitimate full-system scan taking longer than 30 seconds now fails explicitly and can be retried rather than hanging indefinitely. The exact kernel-level NtQueryObject hang is not deterministic in automation, so timeout cleanup is validated with a real blocked child process.

Validation Steps Performed

• Release x64 src/modules/FileLocksmith/FileLocksmithUI/FileLocksmithUI.csproj build: passed; this also builds the FileLocksmithCLI dependency.
• Release x64 src/modules/FileLocksmith/Tests/FileLocksmithUI.UnitTests/FileLocksmithUI.UnitTests.csproj: 6/6 passed, covering success, timeout, malformed output, failed worker exit, no-orphan timeout cleanup, BOM-free Unicode-path communication with the real CLI worker, and kill-on-close job cleanup.
• Release x64 src/modules/FileLocksmith/FileLocksmithCLI/tests/FileLocksmithCLIUnitTests.vcxproj via vstest.console.exe: 6/6 passed.
• Real FileLocksmithCLI.exe --worker-json stdin/stdout smoke query: exit code 0 with valid JSON; malformed worker request: exit code 2.
• Local native/UI builds used /p:SpectreMitigation=false only because this host lacks the Spectre-mitigated MSVC libraries. No production build setting was changed.

[github-actions]

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[github-actions]

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