fix: detect stale PC disconnections

[enaboapps]

Summary

• verify idle BLE connections with a bounded status-characteristic probe
• enter reconnecting before cleanup after native, notification, write, or health-check failures
• defer health checks during protocol work and reset them after healthy activity
• distinguish dropped responses from failed native writes
• add sanitized diagnostics and accessibility and physical-test guidance

Closes #113

Validation

pm run validate (pass: 49 suites, 389 tests, Expo Doctor 21/21)

• focused connection, transport, protocol, and Remote presentation tests (pass: 96 tests before final timeout-cancellation addition)

px expo config --type public (pass; version 1.0.0/build 17 and native configuration unchanged)

• git diff --check (pass)

Physical testing

• Android and iOS checks for PC Quit, PC Disconnect, Bluetooth loss, out-of-range loss, failed writes, dropped responses, announcements, and automatic recovery remain pending. Automated tests use fake BLE transports and do not inject real input.

Compatibility

• no protocol v1, PC application, pairing data, BLE identifier, permission, dependency, native configuration, or version changes

[enaboapps]

Review follow-up at b02640d:\n\n- Resolved the recovery-watchdog timing finding by coordinating health probes before/after background profile requests.\n- Classified pointer-profile native write failures separately so reconnecting begins immediately during both initial negotiation and recovery.\n- Added an absolute 22-second recovery presentation deadline so slow healthy probes cannot prolong the unavailable-state decision.\n- Added regression coverage for stale loss during a pending recovery response, initial/recovery write failures, and slow healthy probes.\n\nValidation: npm run validate passed (49 suites, 393 tests; Expo Doctor 21/21). Independent latest-head re-review and refreshed CI are in progress.

[enaboapps]

Final handoff at b02640d:\n\n- Independent latest-head review: no actionable findings.\n- Local validation: npm run validate passed (49 suites, 393 tests; Expo Doctor 21/21).\n- CI run 32848600621: validate, Android native build, and iOS native build all passed.\n\nThe PR remains draft and unmerged pending explicit approval.