Build, test, and debug regular expressions
Matches Windows-style relative file paths, supporting parent directory traversal (e.g., ..\..\logs), an optional leading .\ or bare backslash, followed by at least one character. The final character must not be a colon, carriage return, or newline, which rejects drive-letter paths like 'C:'. Used with global/multiline flags, it validates relative paths line-by-line, commonly for input validation in .NET applications.