Make relay install lock use idiomatic Effect policies

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What Changed

• Refactored relay client executable/release resolution to use Option instead of null-ish sentinels.
• Reworked relay install lock handling to use Duration, DateTime, and Schedule for stale-lock and retry policy logic.
• Updated relay client tests to use @effect/vitest assert style and Layer.mock for the child process spawner.
• Added deterministic stale-lock coverage using TestClock.

Why

This keeps the relay install path closer to idiomatic Effect patterns and makes time-based lock behavior testable without relying on wall-clock time or ad-hoc millisecond arithmetic.

UI Changes

Not applicable; no UI changes.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes (N/A)
• I included a video for animation/interaction changes (N/A)

Verification

• PATH="/home/ubuntu/.nvm/versions/node/v24.16.0/bin:$PATH" pnpm --dir packages/shared test src/relayClient.test.ts
• PATH="/home/ubuntu/.nvm/versions/node/v24.16.0/bin:$PATH" pnpm exec vp check
• PATH="/home/ubuntu/.nvm/versions/node/v24.16.0/bin:$PATH" pnpm exec vp run typecheck

  

Note

Add stale lock detection and Effect-idiomatic retry scheduling to relay install lock

• Replaces ad-hoc lock retry logic in acquireInstallLock with a typed Schedule that retries on RelayClientInstallLockBusy errors and gives up with install_locked after exhausting attempts.
• Adds isInstallLockStale and attemptAcquireInstallLock helpers that stat the lock file, compute its age using DateTime.distance, and remove it if older than INSTALL_LOCK_STALE_AGE (5 minutes) before retrying acquisition.
• Converts INSTALL_LOCK_RETRY_DELAY and INSTALL_LOCK_STALE_AGE from raw numbers to Duration values, and internal option handling in resolveReleaseAsset and resolvePathExecutable from nullable returns to Option.
• Adds a new test 'removes stale install locks before installing' that backdates a lock file to epoch, advances TestClock by 6 minutes, and asserts the lock is cleared and install succeeds.

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[github-actions]

🚀 Expo continuous deployment is ready!

• Project → t3-code
• Platforms → android, ios
• Scheme → t3code-preview

	🤖 Android	🍎 iOS
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