PR review

Connect GitHub in Settings (device-flow sign-in, or it picks up your gh CLI token automatically). You get:

• Open PRs in the sidebar, from any author on the focused repo, refreshed live.
• One-click review: flock fetches the PR's exact head commit, checks it out locally (fork-safe), and spawns an agent with the review brief.
• CI status for your current branch in the top bar, with a per-check breakdown and a notifications log for check transitions and new PRs.