Add iOS open in browser bridge tests

[YeungKC]

Summary

• Add focused unit coverage for the openInBrowser URL validation contract.
• Add a DEBUG-only UI test harness and UI test for JavaScript posting openInBrowser to the native bridge.
• Add local iOS test scripts and a GitHub Actions entrypoint for the full iOS test suite.

Validation

• Ran the full iOS test entrypoint locally; 8 tests passed.
• Checked that tracked files do not contain a complete Google API key pattern.

Depends on #2073.