Build, test, and debug regular expressions
Validates forum usernames by matching strings containing lowercase letters (a-z), accented vowels (à-ù), digits (0-9), spaces, hyphens, underscores, and the special character ʘ (bilabial click). With the `i` flag, it also matches uppercase equivalents. Typically used to enforce acceptable username formats in forum registration or profile systems that support basic international characters.