feat: Redesign review tab with phase selection, commit navigation, and consolidated toolbar

- Add BranchManager.listCommits() and diffCommit() for commit-level navigation
- Add getPhaseReviewCommits and getCommitDiff tRPC procedures
- New ReviewHeader: consolidated toolbar with phase selector pills, branch info,
  stats, integrated preview controls, and approve/reject actions
- New CommitNav: horizontal commit strip with "All changes" + individual commits,
  each showing hash, message, and change stats
- Slim down ReviewSidebar: file list only with dimming for out-of-scope files
  when viewing a single commit
- ReviewTab orchestrates all pieces in a single bordered card layout

apps/server/git/simple-git-branch-manager.ts

@@ -11,7 +11,7 @@ import { mkdtempSync, rmSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { simpleGit } from 'simple-git';
 import type { BranchManager } from './branch-manager.js';
-import type { MergeResult } from './types.js';
+import type { MergeResult, BranchCommit } from './types.js';
 import { createModuleLogger } from '../logger/index.js';
 
 const log = createModuleLogger('branch-manager');
@@ -116,4 +116,28 @@ export class SimpleGitBranchManager implements BranchManager {
       return false;
     }
   }
+
+  async listCommits(repoPath: string, baseBranch: string, headBranch: string): Promise<BranchCommit[]> {
+    const git = simpleGit(repoPath);
+    const logResult = await git.log({ from: baseBranch, to: headBranch, '--stat': null });
+
+    return logResult.all.map((entry) => {
+      const diffStat = entry.diff;
+      return {
+        hash: entry.hash,
+        shortHash: entry.hash.slice(0, 7),
+        message: entry.message,
+        author: entry.author_name,
+        date: entry.date,
+        filesChanged: diffStat?.files?.length ?? 0,
+        insertions: diffStat?.insertions ?? 0,
+        deletions: diffStat?.deletions ?? 0,
+      };
+    });
+  }
+
+  async diffCommit(repoPath: string, commitHash: string): Promise<string> {
+    const git = simpleGit(repoPath);
+    return git.diff([`${commitHash}~1`, commitHash]);
+  }
 }