fix(desktop): support spaced Windows Git paths in review

[teknium1]

Summary

The Desktop Review pane now works on Windows when Git lives at a path containing spaces (the default C:\Program Files\Git\cmd\git.exe). simple-git's custom-binary validation rejects spaced paths, so every review IPC call threw and the pane silently showed "No diffs" (#54888).

Minimal fix: in gitFor() — the single simple-git constructor all desktop git ops use — when the internally resolved binary contains whitespace, opt into simple-git's supported unsafe.allowUnsafeCustomBinary escape hatch. The binary is resolved in the Electron main process from known install locations or PATH, never renderer/user input, so keeping the trusted absolute path beats falling back to PATH (often absent in GUI-launched apps; PATH lookup could also resolve a repo-local git.exe).

Simplified from #64713 by @unsupportedpastels (authorship preserved): drops the cmd.exe 8.3 short-path conversion layer — the escape hatch alone covers all volumes, including those with 8.3 names disabled. Supersedes #55337 / #60156.

Changes

• apps/desktop/electron/git-review-ops.ts: gitFor() sets unsafe.allowUnsafeCustomBinary only when the resolved binary contains whitespace; gitFor exported for tests
• apps/desktop/electron/git-review-ops.test.ts: constructor accepts a spaced Windows path (all OS); live status() through the real spaced Git for Windows binary (win32-only, skips when absent)

Validation

	Before	After
gitFor(cwd, 'C:\Program Files\Git\cmd\git.exe')	throws GitPluginError	constructs, runs
Non-spaced binaries	validated by simple-git	unchanged (no unsafe flag)
desktop vitest (git-review-ops.test.ts)	—	7/7 pass
tsc -p tsconfig.electron.json --noEmit	—	clean

Fixes #54888

Infographic

[alt-glitch]

This was generated by AI during triage.

Related: this uses simple-git's trusted custom-binary escape hatch, while #64713 also normalizes a Windows short path and #64812 falls back to PATH; maintainer choice is needed.