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/openpyxl/compat/strings.py

@@ -0,0 +1,25 @@
+# Copyright (c) 2010-2024 openpyxl
+
+from datetime import datetime
+from math import isnan, isinf
+import sys
+
+VER = sys.version_info
+
+from .numbers import NUMERIC_TYPES
+
+
+def safe_string(value):
+    """Safely and consistently format numeric values"""
+    if isinstance(value, NUMERIC_TYPES):
+        if isnan(value) or isinf(value):
+            value = ""
+        else:
+            value = "%.16g" % value
+    elif value is None:
+        value = "none"
+    elif isinstance(value, datetime):
+        value = value.isoformat()
+    elif not isinstance(value, str):
+        value = str(value)
+    return value