fix(string-constructor): resolve Optional typing crash and regex warnings

- Fixed TypeError caused by invalid use of typing.Optional with two arguments.
  Replaced Optional[Dict[str, Any], None] with correct Optional[Dict[str, Any]] = None.
- Updated __escape_match() to pass integer brace counts instead of raw strings
  to _n_brackets_after_escape_for_existing_key, preventing runtime errors.
- Converted regex patterns to raw strings (r\'...\') to eliminate SyntaxWarning
  about invalid escape sequences (\\s, \\{).

docstring_formatter.py

@@ -8,16 +8,16 @@ from inspect import getdoc as _getdoc
 import re as _re
 
 
-_re_indent_match = _re.compile("(\t*)( +)(\t*)(.*?)$").match
-_re_tab_indent_match = _re.compile("(\t+)(.*?)$").match
+_re_indent_match = _re.compile(r"(\t*)( +)(\t*)(.*?)$").match
+_re_tab_indent_match = _re.compile(r"(\t+)(.*?)$").match
 _re_list_line_match = _re.compile(
-	"(\s*)("
-	"[-*•]+"
-	"|"
-	"[a-zA-Z]\s*[.)]"
-	"|"
-	"[0-9+]\s*[.)]"
-	")\s+"
+	r"(\s*)("
+	r"[-*•]+"
+	r"|"
+	r"[a-zA-Z]\s*[.)]"
+	r"|"
+	r"[0-9+]\s*[.)]"
+	r")\s+"
 ).match