ci/tasks/readme: register hitbox-tool

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmdG9GqfSWCzts7AkDwRDh

README.md

@@ -12,6 +12,7 @@ agent understands the result without opening an image viewer.
 | [`mesh-tool/`](mesh-tool/) | `mesht` | Creates, inspects and edits 3D models (OBJ + STL). ASCII multi-view rendering + measurements (bbox, volume, watertightness) let an agent *see* a model, edit it (scale/rotate/mirror/merge/primitives) and verify the result. |
 | [`bitmap-font-maker/`](bitmap-font-maker/) | `fontc` | Turns `.font` text files (pixel glyph grids, proportional widths) into font atlases (PNG + JSON metrics) and renders text strings to PNG or the terminal. |
 | [`sfx-maker/`](sfx-maker/) | `sfxc` | Synthesizes retro game sound effects (sfxr-style) from `.sfx` text presets to 16-bit WAV: waves, envelope, pitch slides, vibrato, arpeggio, filters. Deterministic, with built-in presets (jump, coin, laser…). |
+| [`hitbox-tool/`](hitbox-tool/) | `hitbox` | Scans sprite sheet PNGs and writes per-frame collision boxes as JSON from the alpha channel. Understands the spritec sheet naming convention including upscaled sheets. |
 
 Each tool has its own folder, its own README with the full format/CLI
 reference, its own tests and its own dev branch (`dev/<tool>`).