- UiLayer.font_scale: dynamically computed as (ui_height / 200).clamp(2, 6)
Larger screens get bigger UI text automatically
- draw_text: renders each font pixel as font_scale×font_scale block
(was 1×1, now 2×2 to 6×6 depending on screen size)
- text_width: now instance method, returns scaled width
- draw_health_bar: bar width scales with font_scale
- draw_character_panel: panel dimensions and row spacing scale
- draw_hud: bar height, row spacing, bar width scale
- draw_inventory_overlay: slot sizes scale with font_scale
- draw_messages: line spacing scales with font_height
- draw_death_screen: centered text uses scaled text_width
- All 185 tests + 14 scenarios pass
- Benchmark: 61.9 FPS (was 82.7 — 25% regression from more set_alpha calls)