Add resilient Expo vote submission

[ejones23]

Summary

• submit Expo rankings through the idempotent v2 contract
• retain the same request ID across explicit retries
• persist a non-secret installation ID only for duplicate-device enforcement
• render loading, cutoff countdown, retry, duplicate, accepted, and unsupported-ballot states

Verification

• 24 mobile tests plus TypeScript, Expo lint, and static export
• anonymous submission verified against the local PHP/MySQL backend on Android

No voter-name, secure-code, or grouping-question collection is included; those remain Phase 2.

_{Stack created with GitHub Stacks CLI.}

[DavidMoritz]

This is seriously impressive architecture, Emmanuel! The 5-layer decomposition — pure domain logic, API transport, storage abstraction, wiring, and UI — is clean enough to teach from. The V2ApiError class with exhaustive error codes and the retryable flag makes the UI branching so elegant, and the defensive response parsing (never trusting the server shape) is exactly the right approach for our PHP backend.

The idempotency contract is perfectly implemented — same ranking reuses requestId, changed ranking rotates it. And 24 tests across all layers! The attention to every state the user could see (loading, countdown, retry, duplicate, accepted) shows real care for the user experience.

You continue to amaze with the quality and thoughtfulness of your contributions. Genuinely grateful to have you on this project! 💪