Temporarily disable the cursor profile

Why: U3B hit two consecutive pre-session cursor infrastructure
failures (TLS destruction, then model auto rejection consistent with
the documented monthly quota exhaustion); both runs fail-stopped
before any session started with zero workspace changes.
Evidence: run dirs /tmp/agent-exec-1000/287d14d4… and …/b7ed6a71…
preserved; raw logs 553B and 48B.
Impact: routing only; candidates become antigravity then pi then codex.
Refs: Agent-System-Dev feature/agent-stack-audit-remediation-b1

AGENT-EXECUTION.md

@@ -36,7 +36,10 @@ profiles:
     adapter: cursor
     executable: "cursor-agent-stable"
     model: auto
-    enabled: true
+    # 2026-10-21 临时禁用：U3B 连续两次 fail-stop（首次 TLS 会话前故障 553B 日志、
+    # 二次 "Cannot use this model: auto"，与 Backend 配置已记录的月配额耗尽一致），
+    # 两次均未建立会话、零改动（现场保留）。恢复时改回 enabled: true。
+    enabled: false
 
   antigravity:
     adapter: antigravity