ci: add manually-triggered Claude code-review workflow

[jvsena42]

Summary

Adds a Claude-powered code-review bot as a GitHub Actions workflow, triggered manually by the maintainer only.

• Trigger: workflow_dispatch with a pr_number input — a "Run workflow" button in the Actions tab. Only accounts with write access can dispatch, so it's inherently maintainer-only (no comment parsing / actor guard needed).
• Auth: CLAUDE_CODE_OAUTH_TOKEN (Claude subscription token) — no per-use API billing.
• Scope: review only. Job token is limited to contents: read + pull-requests: write; the prompt forbids commits/file changes.
• Output: inline comments on each finding (anchored to file/line) plus one general summary comment.

Matches ci.yml conventions (ubuntu-latest, actions/checkout@v4, two-space indent, name: on each step, concurrency group).

Manual setup required before first run

1. Generate a token locally: claude setup-token (needs Claude Pro/Max).
2. Add it as repo secret CLAUDE_CODE_OAUTH_TOKEN (gh secret set CLAUDE_CODE_OAUTH_TOKEN --repo jvsena42/mandacaru).
3. Ensure Actions → Workflow permissions allows PR writes if reviews fail to post.

Note: workflow_dispatch workflows only appear once this lands on main.

Checklist

• Commits are atomic and follow conventional style
• Unit tests added/updated for business-logic changes — N/A (CI config only)
• Journeys and journeys/README.md testTags updated for UI changes — N/A (no UI change)
• ./gradlew detekt, ./gradlew lintDebug, and ./gradlew test pass locally — N/A (no build impact)
• I have self-reviewed my own diff

Preview

N/A

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