fix(mobile): Persist crash diagnostics before runtime fatals

[juliusmarminge]

Extracted from #3910.

Adds early JS crash capture, disk-backed breadcrumbs, and a synchronous native write path so release-runtime failures leave recoverable diagnostics before React Native terminates. It also records outbox activity as crash context.

Validation inherited from #3910: vp check and mobile native lint passed before the split. The full typecheck is currently blocked in this workspace by unavailable mobile dependencies (expo-blur, expo-quick-actions, and @tabler/icons-react-native).

Note

Persist crash diagnostics to disk before runtime fatals in the mobile app

• Adds a global JS error handler via installCrashLogger that intercepts fatal errors, writes a JSON crash record to the device's crash-logs directory, then delegates to the previous handler.
• Crash files are named crash-<epoch>-<seq>.json for stable lexicographic ordering; on next launch, the most recent 3 are logged to the console and files beyond 20 are pruned.
• installCrashLog.ts is imported at the top of index.ts as a side-effect so the handler registers before any other app modules load.
• Risk: file I/O failures during a crash are silently swallowed; if ErrorUtils is unavailable the installer does nothing.

^{Macroscope summarized 6209d13.}

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Note

Medium Risk
Fatal-error handling performs synchronous document-directory file I/O before the prior global handler runs, which can add latency on the crash path and must not interfere with existing crash reporting.

Overview
Adds early fatal JS crash capture so release-runtime failures leave recoverable diagnostics before React Native tears down.

A side-effect import at the top of index.ts runs installCrashLogger() before the rest of the app loads. The logger chains React Native’s global ErrorUtils handler: on fatal errors it synchronously writes a JSON record (message, name, stack, timestamp) under crash-logs in the document directory, then calls the previous handler. Persistence is wrapped so logging failures never hide the original crash.

On the next launch, a deferred setTimeout(0) pass (no file I/O during install) warns the three newest prior crash files to the console and prunes older logs beyond a cap of 20.

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[macroscopeapp]

Approvability

Verdict: Needs human review

This PR introduces new crash logging infrastructure that installs a global error handler before the app module graph loads. While defensively implemented, changes to fatal error handling at this level warrant human review.

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