fix(browser): stabilize ChatGPT model selection in localized UIs

[dedene]

I noticed the browser mode for oracle was (at least on my side) no longer working with the current ChatGPT interface: the flow gets stuck on the model selection dropdown opening/closing in an endless loop. Also I had to change localization to English before to get it working.

This is my attempt to fix this. Any feedback is welcome! 🙏

Summary

• stop relying on English-only model labels when ChatGPT localizes the model picker and composer footer
• prefer stable data-testid values and selected-row markers when matching the current model
• keep a post-click state-change fallback so selection still settles when the header button stays generic ChatGPT

Verification

• pnpm vitest run tests/browser/modelSelection.test.ts
• pnpm build
• pnpm run oracle -- --engine browser --browser-attach-running --browser-timeout 45s --model gpt-5.4 --prompt "Reply with the exact word ok" --verbose
• pnpm run oracle -- --engine browser --browser-attach-running --browser-timeout 45s --model gpt-5.4-pro --prompt "Reply with the exact word ok" --verbose

Notes

• live browser validation was run against localized ChatGPT UIs in Dutch and French