Emil
d889e24cf6
Each cell now stores its own fg/bg color inline, instead of looking up from MaterialRegistry every frame. Cell struct: - fg: [u8; 3] — foreground color (for rendering) - bg: [u8; 3] — background color (for rendering) - temp: f32 — temperature (already there) - material: MaterialId — for physics property lookup - variant: u8 — visual/behavioral variant - updated_this_tick: bool — CA flag Colors are copied from MaterialRegistry at Cell::new() time. This allows per-cell color variation in the future (water depth shading, lava gradient, damaged materials, etc.) without registry changes. MaterialRegistry still stores physics properties (density, solid, liquid, flammable, etc.) — looked up only during CA/physics steps, not during rendering. Renderers (terminal, ascii, graphics) updated to use cell.fg/cell.bg directly — no more registry lookup in render path. Cell size: ~16 bytes (was ~12). 250x250 grid = 1MB (was 750KB). 126 tests, 0 failures