361 of 614 tile files have .bmp extension but are actually PNG.
Now detects magic bytes and sets correct MIME type per tile.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Extract 614 UB tile BMPs into dungeon_tiles.json (287KB base64 bundle).
Frontend loads tiles once, then draws them rotated per-cell using
environment IDs. Falls back to colored rectangles if tiles not loaded.
Current floor at 70% opacity, other floors at 15%.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>