feat(review,annotate): add Close button to exit sessions without feedback (#523)

Adds a Close button to review and annotation sessions so users can exit
cleanly without sending feedback or killing the agent. Works across all
agent origins and includes a warning dialog when annotations would be lost.

Fixes #522

Co-authored-by: gwynnnplaine <vladyslav.hrabovyii@gmail.com>

packages/server/review.ts

@@ -90,6 +90,7 @@ export interface ReviewServerResult {
     feedback: string;
     annotations: unknown[];
     agentSwitch?: string;
+    exit?: boolean;
   }>;
   /** Stop the server */
   stop: () => void;
@@ -329,12 +330,14 @@ export async function startReviewServer(
     feedback: string;
     annotations: unknown[];
     agentSwitch?: string;
+    exit?: boolean;
   }) => void;
   const decisionPromise = new Promise<{
     approved: boolean;
     feedback: string;
     annotations: unknown[];
     agentSwitch?: string;
+    exit?: boolean;
   }>((resolve) => {
     resolveDecision = resolve;
   });
@@ -560,6 +563,13 @@ export async function startReviewServer(
           });
           if (agentResponse) return agentResponse;
 
+          // API: Exit review session without feedback
+          if (url.pathname === "/api/exit" && req.method === "POST") {
+            deleteDraft(draftKey);
+            resolveDecision({ approved: false, feedback: "", annotations: [], exit: true });
+            return Response.json({ ok: true });
+          }
+
           // API: Submit review feedback
           if (url.pathname === "/api/feedback" && req.method === "POST") {
             try {