[plugins] Add dark-mode logo metadata

[drewschuster-openai]

Adds dark-mode plugin logo metadata to local manifests, remote catalog responses, and the app-server protocol.

What

• Adds nullable logoDark and logoUrlDark fields to PluginInterface.
• Resolves local interface.logoDark assets and maps remote logo_url_dark values.
• Updates the bundled plugin validator and manifest reference.
• Regenerates the app-server JSON schemas and TypeScript types.

Why

Plugin clients need both light and dark logo assets to display a readable brand mark in either theme. The new fields are additive, so clients that do not use them keep the existing logo behavior.

How

Local plugin manifests expose interface.logoDark as a package-relative asset path. Remote plugin catalog responses expose logo_url_dark. Both values map into separate app-server fields so clients can preserve local-path and remote-URL handling.

Testing

• just test -p codex-app-server-protocol
• just test -p codex-core-plugins
• just test -p codex-app-server
• just test -p codex-plugin
• just test -p codex-skills
• cargo build --bin codex
• Validated a local plugin manifest containing interface.logoDark with the bundled validator.
• Ran the required scoped just fix commands and just fmt.

Manual verification

Create a local plugin with both interface.logo and interface.logoDark, then call plugin/list or plugin/read. Confirm that the response contains separate logo and logoDark paths. For a remote catalog entry, confirm that logoUrlDark is populated from logo_url_dark.

Risk

The app-server change is additive and nullable. The main risk is an incomplete mapping path, covered by local-manifest, remote-catalog, protocol serialization, and app-server integration tests.

Spiciness: 2/5

Issue: N/A — coordinated maintainer change.

[github-actions]

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[chatgpt-codex-connector]

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[drewschuster-openai]

I have read the CLA Document and I hereby sign the CLA