📏 Handle Rules Linter
Check a desired handle against every platform's username rules and find the form that works everywhere. Flags handles that break a platform's length limits, use a disallowed character (like a period on YouTube or TikTok), or start with a disallowed character, and recommends the safe consistent form (4 to 15 lowercase alphanumeric). Covers X, Instagram, TikTok, YouTube, Twitch, GitHub, and Bluesky. It checks the rules, not availability.