Add resolution options to character select screen

Update CLAUDE.md with sprite pipeline and revised architecture notes

Replace procedural character art with PNG sprite rendering

Rework all sprite art to chibi cartoon style matching character references

Make index.html fully self-contained by inlining CSS and JS

Add canonical ES module source files (reference, not loaded by browser)

Add complete game bundle: all systems, entities, and rendering in one file

Add project foundation: HTML entry point, CSS layout, and documentation