Temporarily disable the exhausted cursor profile for backend dispatch

Why: the cursor account hit its monthly usage limit (resets 2026-11-10);
attempts fail before useful work. Routing falls through to antigravity and
pi per the existing candidate order; re-enable when the quota resets.
Reason recorded on the U3 task card.

Impact: AGENT-EXECUTION.md only (rides the U3 PR, auditable).

Refs: plan 2026-10-19-1440 U3.

AGENT-EXECUTION.md

@@ -36,7 +36,9 @@ profiles:
     adapter: cursor
     executable: "cursor-agent-stable"
     model: auto
-    enabled: true
+    # 2026-10-20 临时禁用：cursor 账本月配额耗尽（重置 2026-11-10），原因记录于
+    # Dev U3 任务卡；恢复时改回 enabled: true。
+    enabled: false
 
   antigravity:
     adapter: antigravity