fix(lint): _subsets 移除未用的 _harness re-export 符号（ruff F401×4）

Author: loong10k

tests/_subsets.py

@@ -12,8 +12,7 @@
 import tempfile
 from pathlib import Path
 
-from _harness import FAIL, HOOKS, PASS, PLUGIN, SKIP, git, make_repo, ok, run_hook, skip
-
+from _harness import HOOKS, PLUGIN, git, make_repo, ok, run_hook, skip
 
 # ══════════════════════════ 子集 1：语言规则结构审计 ══════════════════════════