Improve Chromium browser detection reliability

Some Chromium-based browsers aren't reliably detected for caption capture. Reported issues:

• Vivaldi Snapshot (beta channel) not detected at all

• Zen Browser detected a Google Meet call but no caption text was captured

The stable versions of Chrome, Edge, Arc, Brave, Vivaldi, and Opera are supported, but variant channels (Canary, Beta, Snapshot, Nightly) and less common Chromium browsers may not work. Looking into making detection more robust so it works across more Chromium variants without needing manual updates.