Emil
b52798c634
Replaced HashMap<(i32,i32), UiCell> with Vec<Option<UiCell>> indexed by y*width+x. dirty_keys Vec tracks non-None cells for iteration. - set/set_alpha: O(1) array write (was O(1) amortized HashMap insert with hashing overhead) - get: O(1) array index (was HashMap lookup) - keys(): iterate dirty_keys Vec (was HashMap keys iterator) - clear(): memset None over flat array (was HashMap::clear) - resize() called in build_ui to size array to viewport - All 185 tests + 14 scenarios pass - Benchmark: 95.1 FPS (was 61.9 — 53% improvement)
