feat(review): [optional] Add opt-out for platform review attribution

[leoreisdias]

Context

Plannotator currently adds Review from Plannotator to GitHub and GitLab review bodies whenever a review is submitted from the code-review UI. That attribution is useful as a consistent product signal, but some users may prefer PR/MR comments to read as plain review text without the tool signature.

This PR keeps the current behavior as the default and adds a small review-mode preference for opting out.

If Plannotator wants to keep its presence consistent in platform comments and not offer an opt-out, this PR is totally fine to ignore. I can see the product argument either way; this is just the quieter-comments version.

What Changed

• Added a persisted platformReviewAttribution config setting, defaulting to true.
• Added a Review mode Settings -> Comments toggle labeled "Plannotator Attribution".
• Changed the GitHub/GitLab review body builder to include Review from Plannotator only when that setting is enabled.
• Threaded the setting through the Bun and Pi config endpoints so it persists via ~/.plannotator/config.json across runtimes.

Screenshot

Review Focus

The main behavior to check is that the default remains unchanged: existing users should still get Review from Plannotator unless they explicitly disable the new setting.

The config plumbing is intentionally broad because the shared settings UI can be hosted by plan, annotate, review, and Pi runtime servers. Review the /api/config handlers if you want to make sure the setting persists consistently across those surfaces.

Test Plan

• Ran the repo TypeScript project checks via bunx --package typescript tsc for core, shared, ai, server, ui, strict consumer, and Pi projects.
• Ran bun run build:review && bun run build:hook so the local CLI served the updated review UI.
• Ran plannotator review on this worktree; review completed with no changes requested.
• Ran ./bin/plannotator.js review https://github.com/Lexamica/lexamica-refer/pull/1167 to exercise the local CLI PR review flow; it opened the PR review UI and successfully approved the PR on GitHub.