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/trpc/routers/phase.ts

@@ -234,5 +234,69 @@ export function phaseProcedures(publicProcedure: ProcedureBuilder) {
         await orchestrator.approveAndMergePhase(input.phaseId);
         return { success: true };
       }),
+
+    getPhaseReviewCommits: publicProcedure
+      .input(z.object({ phaseId: z.string().min(1) }))
+      .query(async ({ ctx, input }) => {
+        const phaseRepo = requirePhaseRepository(ctx);
+        const initiativeRepo = requireInitiativeRepository(ctx);
+        const projectRepo = requireProjectRepository(ctx);
+        const branchManager = requireBranchManager(ctx);
+
+        const phase = await phaseRepo.findById(input.phaseId);
+        if (!phase) {
+          throw new TRPCError({ code: 'NOT_FOUND', message: `Phase '${input.phaseId}' not found` });
+        }
+        if (phase.status !== 'pending_review') {
+          throw new TRPCError({ code: 'BAD_REQUEST', message: `Phase is not pending review (status: ${phase.status})` });
+        }
+
+        const initiative = await initiativeRepo.findById(phase.initiativeId);
+        if (!initiative?.branch) {
+          throw new TRPCError({ code: 'BAD_REQUEST', message: 'Initiative has no branch configured' });
+        }
+
+        const initBranch = initiative.branch;
+        const phBranch = phaseBranchName(initBranch, phase.name);
+        const projects = await projectRepo.findProjectsByInitiativeId(phase.initiativeId);
+
+        const allCommits: Array<{ hash: string; shortHash: string; message: string; author: string; date: string; filesChanged: number; insertions: number; deletions: number }> = [];
+
+        for (const project of projects) {
+          const clonePath = await ensureProjectClone(project, ctx.workspaceRoot!);
+          const commits = await branchManager.listCommits(clonePath, initBranch, phBranch);
+          allCommits.push(...commits);
+        }
+
+        return { commits: allCommits, sourceBranch: phBranch, targetBranch: initBranch };
+      }),
+
+    getCommitDiff: publicProcedure
+      .input(z.object({ phaseId: z.string().min(1), commitHash: z.string().min(1) }))
+      .query(async ({ ctx, input }) => {
+        const phaseRepo = requirePhaseRepository(ctx);
+        const projectRepo = requireProjectRepository(ctx);
+        const branchManager = requireBranchManager(ctx);
+
+        const phase = await phaseRepo.findById(input.phaseId);
+        if (!phase) {
+          throw new TRPCError({ code: 'NOT_FOUND', message: `Phase '${input.phaseId}' not found` });
+        }
+
+        const projects = await projectRepo.findProjectsByInitiativeId(phase.initiativeId);
+        let rawDiff = '';
+
+        for (const project of projects) {
+          const clonePath = await ensureProjectClone(project, ctx.workspaceRoot!);
+          try {
+            const diff = await branchManager.diffCommit(clonePath, input.commitHash);
+            if (diff) rawDiff += diff + '\n';
+          } catch {
+            // commit not in this project clone
+          }
+        }
+
+        return { rawDiff };
+      }),
   };
 }