- Replace hardcoded 80-char limit with admin-configurable setting
- Add settings form at /admin/config/media/filename-length-limiter
- Resolve filename collisions by appending numeric suffixes
- Display warning message to user when truncation occurs
- Add README, AFL-3.0 license, and CLAUDE.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>