UI in device pixels on the character grid with fixed integer font sizes, ASCII bars; 3D render scale for a pixel look

- text only at 1x/2x/4x times an integer interface factor (auto or 1-4 in the settings)
- high DPI rendering, own 2D camera in device pixels, mouse converted
- toolbar buttons 6 columns, integer icon scale, minimap integer pixels per tile
- all bars (top bar, unit/tower/gate HP) as CP437 block characters
- 3D world optionally rendered at 1/2, 1/3, 1/4 and upscaled with nearest filtering

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

DESIGN.md

@@ -6,7 +6,10 @@ An original dungeon management game (genre: dungeon building & defence) that run
 - Rust + **macroquad** (WebGL), target `wasm32-unknown-unknown`
 - User interface drawn entirely **in the canvas**
 - Font: **DINOBYTE** bitmap font (CP437, 6×8 px, CC BY 4.0, see CREDITS.md) for all texts, integer scaled
-- All UI windows use **CP437 frames** (single lines for panels, double lines for dialogs); bars (HP/mana/gate) are pixel bars
+- All UI windows use **CP437 frames** (single lines for panels, double lines for dialogs); **all bars are CP437 block characters** (█ ▌ ░)
+- Text only in **fixed integer sizes**: 1×, 2× and 4× the 6×8 glyph size, times an integer **interface factor** (automatic from the device resolution, or 1×–4× in the settings)
+- The interface is drawn in **device pixels** (high DPI) and laid out on the **character grid**, so every font pixel has exactly the same size
+- **3D resolution** setting: the world can be rendered at 1/1, 1/2, 1/3 or 1/4 resolution and scaled up by exactly that factor (pixel look); the interface stays sharp
 - Sound: event system + macroquad audio prepared (volume, mute key M); sounds will be generated later
 - Languages: all in-game texts live in **language files** (`lang/*.lang`, key = text); English is the reference/fallback, German included, more can be added. The language is chosen on first start and stored in the browser.
 - Repository language: **English** (code, comments, docs, commit messages)