Adopt shared CodeRabbit review commands from research-repo-tools

[acgetchell]

Goal

Adopt the shared CodeRabbit review capability from acgetchell/research-repo-tools#5 through thin just review [base] and just review-uncommitted recipes in this repository. This is a separate review-adoption issue; general maintenance and toolchain migration remains in #615.

Prerequisite and rollout

The shared implementation in acgetchell/research-repo-tools#5 must be ready, and a release containing the review commands must be available on PyPI before production adoption. Pin that exact version in the tooling dependency group included by dev and update the lockfile. Do not assume the first package release contains this capability. A local wheel may be used for pilot comparison, but committed dependencies and CI must use the published package.

Coordinate with #614: adopting the shared implementation can satisfy its live-base requirements. If #614 lands first, replace its local helper after verifying equivalent behavior. That local fix remains independently actionable; do not implement the same scope twice.

Scope

• Use the shared public CLI for branch and uncommitted scopes; keep all common scope, freshness, instruction discovery, subprocess, and error handling upstream.
• Default branch review to origin/main, verified against the live remote at invocation. Include committed branch changes, staged/unstaged changes, and non-ignored untracked files. Preserve explicit local-base overrides and uncommitted-only review without remote freshness checks.
• Use the shared structured output and configuration discovery contract with this repository's instructions. Preserve streamed output, interruption, and failures; unavailable reviews must not appear clean.
• Keep CodeRabbit externally installed and authenticated. Review remains opt-in, outside check/ci, with explicit maintainer authorization for agent invocation. No implicit installation, authentication, paid-credit enabling, retries, or Git mutations.
• Document prerequisites, scopes, freshness diagnostics, and dependency updates; expose both recipes in help using the repository's command conventions.
• Port applicable common regressions upstream before deleting duplicated helpers or tests. Retain focused consumer tests for recipe wiring, configuration discovery, argument forwarding, and failure propagation using local stubs. Keep helpers still needed by other callers.

Acceptance criteria

• A clean environment installs the locked release from PyPI and discovers both Just recipes.
• Both recipes call the same shared implementation with the intended scope, base, and repository instructions.
• Focused integration checks verify the pinned package and consumer wiring without contacting CodeRabbit.
• Applicable consumer checks, final CI, and the supported platform matrix pass; package tests alone are insufficient adoption evidence.
• Superseded review implementation and dedicated tests are removed after their applicable regressions are preserved upstream.
• Help and contributor documentation describe the final workflow and deliberate behavior changes.

A live CodeRabbit smoke review is separate, explicitly authorized work; it is not an automatic validation step.