v0.1.0-canary.4

Summary

Adding universal Google Sign-In support across Android and iOS with a shared bridge contract.

Problem

Apps needed a consistent, native Google authentication flow in Catalyst across both platforms, with minimal web-side differences.

Solution

Implemented Google Sign-In end-to-end in native layers and bridge APIs:

1. Android: Google Sign-In via Credential Manager + Google Identity Services
2. iOS: Google Sign-In via latest GoogleSignIn SDK (signIn(withPresenting:))
3. Shared config gate: googleSignIn.enabled + googleSignIn.clientId (with optional web override)
4. Standardized web hook/bridge flow (googleSignIn command + success/error/cancel callbacks)
5. Standardized success payload: { idToken, email?, name?, photoUrl?, provider: "google" }

Impact

1. Unified “Continue with Google” experience on Android and iOS
2. Cleaner integration for app developers through one bridge contract
3. Better release/build reliability from related bridge/build updates included in the same merge