按评审意见强化回退模板读取通道回归测试

- tests/configuration.rs 回退模板测试改用与模板无关的 runtime dir，分类断言覆盖按路径归属而非 runtime dir 为 None 的恒真分支，并补充 runtime dir 内路径的 managed 正向断言
- tests/mod.rs 移除不再使用的 clear_test_runtime_config_dir 辅助

apps/ai-game-creator-shell/src-tauri/src/tests/configuration.rs

@@ -1195,15 +1195,23 @@ fn fallback_template_read_stays_on_snapshot_channel_outside_runtime_dir() {
         "{\n  \"llm\": { \"model\": \"fallback-template-model\" }\n}\n",
     )
     .expect("write fallback template");
-    let _guard = clear_test_runtime_config_dir();
+    // 设置一个与模板无关的 runtime dir，让分类断言真正覆盖"按路径归属"而非
+    // "runtime dir 为 None 时恒 false"的全局开关。
+    let runtime_root = unique_project_path();
+    fs::create_dir_all(&runtime_root).expect("unrelated runtime config dir");
+    let _guard = use_test_runtime_config_dir(runtime_root.clone());
 
     // 仓库旁边的回退模板是共享输入，读取绝不能走会收紧 owner/DACL 的私有通道。
     assert!(!game_creator_config_path_is_runtime_managed(&template));
+    assert!(game_creator_config_path_is_runtime_managed(
+        &runtime_root.join(GAME_CREATOR_CONFIG_FILE_NAME)
+    ));
     let content = read_game_creator_config_file(&template).expect("read fallback template");
     assert!(content
         .expect("fallback template content")
         .contains("fallback-template-model"));
     fs::remove_dir_all(root).ok();
+    fs::remove_dir_all(runtime_root).ok();
 }
 
 #[test]

apps/ai-game-creator-shell/src-tauri/src/tests/mod.rs

@@ -1327,20 +1327,6 @@ fn use_test_runtime_config_dir(path: PathBuf) -> TestRuntimeConfigDirGuard {
     }
 }
 
-fn clear_test_runtime_config_dir() -> TestRuntimeConfigDirGuard {
-    let lock = TEST_CONFIG_LOCK
-        .lock()
-        .unwrap_or_else(|poisoned| poisoned.into_inner());
-    let previous = game_creator_runtime_config_dir();
-    *game_creator_runtime_config_dir_lock()
-        .lock()
-        .expect("runtime config dir lock") = None;
-    TestRuntimeConfigDirGuard {
-        _lock: lock,
-        previous,
-    }
-}
-
 fn assert_task_status(manifest: &Value, task_id: &str, status: &str) {
     let task = manifest["tasks"]
         .as_array()