refactor: replace SensorBox architecture - #44

This PR replaces the 30 lower layers in the original SensorBox refactor stack, PRs #14 through #43. PR #44 is now the only review target.

The base is master, so GitHub's Files changed view shows the final repository state. Intermediate interfaces and implementations removed by the architecture pass are not part of the review diff.

What changed

• Added the pure Kotlin core-common and recording-core modules.
• Standardized expected outcomes on AppResult<T> with stable, data-only application errors.
• Added private rotating diagnostics that users can view, copy, share, export, or clear from Settings.
• Kept Android recording adapters in sensorservices and removed its Wear transport dependency.
• Replaced the Wear command protocol with strict version 2 prepare, commit, abort, stop, and correlated acknowledgements.
• Added phone-owned, all-or-nothing paired recording coordination with stable source order, retries, timeouts, and compensation.
• Split phone presentation state by onboarding, recording, and settings workflows.
• Moved command behavior into typed phone and watch handlers, leaving listener services as decode-and-dispatch boundaries.
• Added ADRs and the implementation checklist in docs/architecture-refactor-plan.md.

Earlier review feedback

PR #14 contains the only review threads in the old stack. Its AppDiagnostics threads target a class deleted by this change and replaced by FileDiagnostics plus the Settings diagnostics flow. The preference grouping and NativeDocumentStorage API notes still refer to current code, so they remain visible in #14 and should be judged against their current implementations in this PR.

Validation

• ./gradlew testDebugUnitTest lintDebug assembleDebugAndroidTest assembleDebug detekt
• ./gradlew :core-common:test :recording-core:test
• tools/emulator/run_phone_sensor_test.sh: OK (1 test)
• Wear-to-phone APKs and instrumentation suites compile. The runtime workflow reaches its pairing precondition, but SensorBox_Wear_API_37 still needs one-time phone/watch pairing in Android Studio before tools/emulator/run_wear_sync_test.sh can run.