Adds the design for a live browser-based dungeon generator: reikhelm-core
compiled to WASM (after dropping the unused rand dep), a thin reikhelm-wasm
bridge, and a vanilla-JS/Canvas atmospheric renderer driven + screenshotted
via Playwright. Plus C2: room shape variety (rect/octagon/ellipse/plus) to
escape rectangular rooms. Aesthetic target: atmospheric + polygonal.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
