Improve CI reliability and efficiency

[HamdaanAliQuatil]

CI is unreliable: tests fail randomly, then pass without code changes. Multiple issues:

• Tests run 2-3 times per job (VM twice, Chrome twice)
• Separate coverage jobs duplicate all test runs
• macOS times out after 15 minutes
• Mobile emulators are flaky

We plan to ship it in two parts:

Structural Cleanup:

• Add concurrency group (cancel superseded runs)
• Remove macos-14 (duplicate of macos-15)
• Merge linux-coverage and windows-coverage into main jobs
• Fix redundant test runs (VM/Chrome now run once per job)
• Make iOS/Android non-blocking (continue-on-error: true)

Emulator Reliability:
The goal is to make mobile tests deterministic by enabling retries and improving infrastructure.

Android

• Downgrade API 36 to 34 (36 has a known emulator issue; need to evaluate if it was upgraded for a specific reason)
• Cache AVD snapshots (actions/cache@v4)
• Add headless flags: -no-window -gpu swiftshader_indirect -noaudio
• Add 3-attempt retry loop

iOS

• Add 2-attempt retry wrapper (nick-fields/retry@v3)

Future Discussion:

• Debug macOS WASM hang (causes 15min timeout)
• Evaluate if Firefox is needed on all platforms
• Consider Linux-only coverage

Open for opinions