Firemark turns watermark removal into stress test

This is less a watermark remover challenge than a demo of how far visible, adversarially hardened document watermarking can go before AI cleanup starts to win. The repo markets Firemark as a fast, single-binary Rust tool with 17 visible styles and batch processing, and its newer docs claim per-render randomness plus AI-removal hardening via alpha jitter, sub-pixel noise, ghost pixels, and prompt-injection strips.