bump: minor
type: feat
Incremental asset preloading (#82). Assets used to load synchronously inside Boot/Start (`png_load`, `Audio.load`), stalling the first frame(s) as content grows, with no built-in loading phase. Adds an `Assets.*` preload queue: `Assets.enqueue(name, path)` queues a named image without loading it, `Assets.pump(max)` loads up to `max` queued assets per frame (returning how many it loaded), and `Assets.total` / `loaded` / `ready` / `progress` (0..100) drive a progress bar. A loading scene pumps a few assets per frame, draws `Assets.progress()`, and `become`s the play scene once `Assets.ready()`, so the game shows a responsive loading screen and only enters play once content is ready — the deterministic, no-threads form of async preloading (the work is spread across frames instead of stalling one, and the same enqueue+pump order loads identically every run). Loaded assets are reachable by name via `Assets.get` / `Sprite.named`. Builds on the #81 atlas. Example: `examples/library/preload.ludic`.