Support standalone Codex updates and show update progress

[lynnswap]

Closes #390

Purpose

ReviewMonitor now checks and updates standalone Codex installations using the selected CLI's installation home, instead of rejecting them or passing the isolated review home. The sidebar Update button shows a spinner and the current stage while Codex stops, installs, and restarts.

Changes

• Share executable selection with the review runtime and preserve the stable launcher so restarting resolves the updated release.
• Derive standalone installation homes from the selected executable, including custom homes and directory aliases, and target the selected launcher directory when installing. Reviews retain their isolated home.
• Keep successfully fetched version availability visible with manual-update guidance when automatic installation is unsupported. Preserve interpreter lookup for script-based checks while retaining the selected installation's PATH for updates.
• Replace the active update button with a sized progress view and stage label, using the existing store lifecycle.

Review focus

Installation targeting for standalone and Homebrew CLIs, stable-launcher handling, and preservation of review deferral, queued requests, and runtime restart behavior.

Screenshots

No screenshot attached; UI preview rendering remains unverified. Automated UI tests cover toolbar progress presentation and nonzero layout size.

Testing

• swift test --build-system swiftbuild --no-parallel: all 1,256 package tests passed.
• xcodebuild test -project Tools/ReviewMonitor/CodexReviewMonitor.xcodeproj -scheme CodexReviewMonitor -destination 'platform=macOS,arch=arm64' -skipMacroValidation CODE_SIGNING_ALLOWED=NO CODE_SIGNING_REQUIRED=NO: all app tests passed. Macro validation uses the same opt-out as repository CI.
• Regression coverage includes separate review/installation homes, symlinked custom homes, failed version probes, npm interpreter lookup, launcher refresh after a fixture update, and toolbar progress layout.
• git diff --check: passed.
• codex-review of the final diff: completed with no findings (job 80224CD6-D33D-4025-874B-76B12A08EB65).

Installation targeting and launcher refresh were verified with fixture CLI processes; an actual Codex package update was not performed.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-03T06:29:38.478982Z	3efab58	PR opened
🔒 Security Review	✅ Completed 2026-10-03T06:28:47.713719Z	3efab58	PR opened

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