[codex] Reduce OpenAI dashboard scrape payload

[jb510]

Summary

• Extract OpenAI auth status, signed-in email, and account plan inside the WebView scrape script.
• Stop returning full document.documentElement.outerHTML during normal OpenAI dashboard polling.
• Fetch full HTML only when debugDumpHTML is enabled for diagnostic failure paths.
• Add WebKit coverage proving the scrape returns structured account fields and omits bodyHTML.

Closes #1033.

Why

Sampling a high-CPU CodexBar refresh showed the OpenAI web path spending time serializing/parsing full dashboard HTML and reparsing embedded bootstrap JSON in Swift. The normal refresh path only needs a few structured values from that HTML, so returning the full DOM on every poll is avoidable work.

Testing

• swift test --filter OpenAIDashboardScrapeScriptTests
• swift test --filter OpenAIDashboardFetcherCreditsWaitTests
• swift test --filter OpenAIDashboardParserTests
• make check
• CODEXBAR_SIGNING=adhoc CODEXBAR_WIDGET_METADATA_MODE=skip ./Scripts/package_app.sh release

Full Suite Note

swift test was run and reached 2722 tests, but reported 2 failures outside this change area:

• MistralUsageParserTests.swift:115: expected month 11, observed 10
• ProviderStorageFootprintTests.swift:401: expected generation 41, observed 42

The OpenAI web-focused tests passed after the scrape-payload change.

Local Test Status

Built and installed locally for manual validation from branch perf/openai-web-scrape-payload.

[steipete]

Thanks @jb510, landed this on main as ff1a169c with the maintainer changelog in 5aca0cd6.

I could not update the contributor branch directly, so I rebased and landed the reviewed patch from a maintainer branch while preserving the original commit author. Local proof before landing:

• swift test --filter OpenAIDashboardScrapeScriptTests
• swift test --filter OpenAIDashboardFetcherCreditsWaitTests
• swift test --filter OpenAIDashboardParserTests
• make check
• Codex review clean