Pass the exec-tool kill switch into the clean serve process

Why: env -i dropped RDM_DISABLE_EXEC_TOOLS, so the real RDM binary exited immediately on runners without bwrap, and the capability probe now prints the JSON document.
Evidence: SELF bash -n scripts/svc.sh; python3 -m py_compile tests/test_svc_realcombo.py. GATE run 2656 job 3831 failed on the previous head before this fix.
Impact: serve and the lifecycle child forward that one switch; identity capabilities is checked as protocol 1 JSON.
Refs: #485
Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/svc.sh

@@ -1396,11 +1396,15 @@ svc_launch_serve() {
   fi
   # 桩只靠 SVC_STUB_* 找到记录目录。这些变量不写入 serve.env，避免 recover
   # 把某次测试路径固化进实例；生产调用方没有它们。
+  # RDM_DISABLE_EXEC_TOOLS 是产品兜底开关，必须到达 serve，否则无 bwrap 时拒启。
   local k
   while IFS= read -r k; do
     [ -n "$k" ] || continue
     args+=("$k=${!k}")
   done < <(compgen -e | grep -E '^SVC_STUB_' || true)
+  if [ -n "${RDM_DISABLE_EXEC_TOOLS:-}" ]; then
+    args+=("RDM_DISABLE_EXEC_TOOLS=$RDM_DISABLE_EXEC_TOOLS")
+  fi
   # shellcheck disable=SC2086
   nohup "${args[@]}" "$ENV_BIN" serve $exec_args >> "$ENV_DIR/svc.log" 2>&1 9>&- &
 }
@@ -1422,6 +1426,9 @@ svc_lifecycle_child() {
     [ -n "$k" ] || continue
     args+=("$k=${!k}")
   done < <(compgen -e | grep -E '^(SVC_|LC_)' || true)
+  if [ -n "${RDM_DISABLE_EXEC_TOOLS:-}" ]; then
+    args+=("RDM_DISABLE_EXEC_TOOLS=$RDM_DISABLE_EXEC_TOOLS")
+  fi
   args+=(bash "$0" __lifecycle "$@")
   "${args[@]}"
 }

tests/test_svc_realcombo.py

@@ -134,7 +134,11 @@ class RealComboTests(tsr.SvcAutoRecoverTests):
                               "identity", "capabilities"],
                              capture_output=True, text=True, timeout=15)
         self.assertEqual(cap.returncode, 0, cap.stderr)
-        self.assertIn("identity-capabilities: v1", cap.stdout)
+        doc = json.loads(cap.stdout)
+        self.assertEqual(doc["protocol"], 1)
+        self.assertEqual(doc["identity"]["open"], "existing-no-migrate")
+        self.assertIn("ensure", doc["identity"]["ops"])
+        self.assertIn("verify", doc["identity"]["ops"])
         # 错 id verify 拒绝
         bad = subprocess.run([str(self.runtime("rc1") / "bin" / "agent-system"),
                               "identity", "verify", "--instance-id",