Hot reload on every layer

If I'm going to spend a year writing this thing, I want the iteration loop to feel instant. So every layer of the engine hot-reloads on save:

• UI / TSX -> the JSX bundle re-evals inside the wasm and the reactive runtime (written in TS) re-mounts the diffed tree. Same trick the desktop dev binary uses
• Native C code -> the game ships as a .dylib next to the shell binary. On every save, the shell re-dlopens the new dylib (with a generation-suffixed copy per load to defeat macOS dyld same-path pinning, that was a fun afternoon)
• Shaders -> .glsl edits regenerate the .glsl.h header, dev-watch.sh fingerprints the UBO layout and decides between hot reload (shader body only) or full reload (struct changed)
• Scenes -> scene_reload reads the .scene.json again and reconciles entities in place. Move a ship, adjust a spawner, no restart
• Audio assets -> filewatch on the voice + track files, the running mix picks up the new note instantly

The whole loop is driven by a tiny dev-watch.sh that writes .reload-hot / .reload-full signal files. The engine watches those files and dispatches the right reload phase.

End result: I can have the game running, the music playing, and edit a shader, a C system, the JSX HUD, and a scene at the same time, watching the changes land without losing a frame :)