[codex] Fix Google Photos Picker discovery

[zrm625]

Summary

Fix Google APIs whose live Discovery documents only work at their service-hosted URL. This covers Google Photos Picker, Forms, and Keep. Also show required OAuth scopes in the generic OAuth app registration form.

Bug

I added Google Photos Picker support and the Picker bug in the same PR, so there was never a known-good upstream Picker path.

Picker's live Discovery URL is https://photospicker.googleapis.com/$discovery/rest?version=v1; the rewritten central URL returns 404. Its live document also omits OAuth scope metadata, so Picker could be added without the required https://www.googleapis.com/auth/photospicker.mediaitems.readonly scope.

The test fixture missed this because it was more complete than Google's live document. While validating the deployed fix, the default Google bundle exposed the same service-hosted-only Discovery issue for Forms and Keep.

Introduced in: RhysSullivan#1137
Related normalizer change: RhysSullivan#1106

Fix

• Keep Picker, Forms, and Keep service-hosted Discovery URLs service-hosted.
• Keep Picker's documented OAuth scope fallback in the same override map.
• Leave normal central Discovery behavior in place for other Google APIs.
• Show required OAuth scopes during manual OAuth app registration.

The UI change is disclosure-only. It does not request new permissions.

Screenshot

Validation

• bun run --cwd packages/plugins/google test -- src/sdk/discovery.test.ts src/sdk/plugin.test.ts
• bun run --cwd packages/react test -- src/components/oauth-client-form.test.ts
• Live deploy smoke on executor v1.5.23: / returns 200 and /mcp returns unauthenticated 401.
• Live default Google bundle replay returned 200 with 264 tools.

[zrm625]

@codex

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Bravo.

Reviewed commit: 38a17ede4a

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