Track generated AGENTS.md plugin outputs

[chubes4]

Summary

• track eight canonical AGENTS.md files already generated and verified by the plugin build
• make a clean pnpm build leave the publication workspace unchanged
• preserve WP Codebox integrity enforcement instead of excluding legitimate package outputs

Closes #117.

Root cause

The build and verification scripts generate and require these package files, and repository documentation advertises them, but only the OpenClaw equivalent was tracked. git diff does not report untracked files, so the scoped drift check passed while WP Codebox correctly rejected publication after detecting the eight additions in its complete workspace snapshot.

Diagnostic run: https://github.com/Automattic/build-with-wordpress/actions/runs/29643902298

How to test

1. Run pnpm install --frozen-lockfile.
2. Run pnpm build.
3. Run pnpm verify.
4. Run git diff --exit-code and confirm the build leaves no tracked changes.
5. Run git ls-files plugins/amp/AGENTS.md plugins/devin/AGENTS.md plugins/junie/.junie/AGENTS.md plugins/kilo-code/AGENTS.md plugins/opencode/AGENTS.md plugins/qodo/AGENTS.md plugins/roo-code/AGENTS.md plugins/zed/AGENTS.md and confirm all eight paths are tracked.

Compatibility

• No public API or extension behavior changes.
• This changes package contents only by including files the existing build already generates and verification already requires.

AI assistance

• AI assistance: Yes
• Tool(s): OpenAI GPT-5.6 Sol via OpenCode
• Used for: Diagnosed the integrity evidence, prepared and verified the generated output candidate, and drafted this PR with Chris reviewing and owning the change.