chore(theme): astro 锁定 ~5.18.0（终审 Minor）+ docs: Plan 4 收官

Co-Authored-By: Claude Code <noreply@anthropic.com>

.deps_siteforge_v812/_pytest/config/exceptions.py

@@ -0,0 +1,15 @@
+from __future__ import annotations
+
+from typing import final
+
+
+@final
+class UsageError(Exception):
+    """Error in pytest usage or invocation."""
+
+    __module__ = "pytest"
+
+
+class PrintHelp(Exception):
+    """Raised when pytest should print its help to skip the rest of the
+    argument parsing and validation."""