Include plugin IDs in hook run summaries

[abhinav-oai]

Why

Desktop clients only receive the coarse plugin hook source for hook runs. That is not enough to identify which plugin produced a blocked hook, so clients can only open the aggregate plugin settings view.

What

• Add pluginId to core and app-server v2 hook run summaries.
• Propagate the plugin identity from discovered handlers into started and completed hook notifications.
• Regenerate the app-server schemas and document the notification field.

Validation

• cargo nextest run -p codex-hooks --no-default-features
• cargo nextest run -p codex-app-server-protocol
• Verified end to end with a local Codex CLI build and the Codex desktop dev app.