Interface size setting: auto, large, medium or small on the world's pixel grid

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

src/main.rs

@@ -976,8 +976,12 @@ async fn main() {
         // 1080 device rows in landscape; a smaller screen draws in device pixels)
         let need: u32 = 900;
         // measured on the shorter side: upright (portrait) the width gets those pixels and the
-        // height grows with the screen, so the world and the menus keep their size
-        let short = rows * need.div_ceil(rows);
+        // height grows with the screen, so the world and the menus keep their size. The setting
+        // "interface size" picks the interface pixels per world pixel: large 2, medium 3, small 4
+        let short = match app.settings.ui_factor {
+            k @ 2..=4 => rows * k as u32,
+            _ => rows * need.div_ceil(rows),
+        };
         let (w, h) = (screen_width().max(1.0), screen_height().max(1.0));
         let vrows = if h > w { (short as f32 * h / w).round() as u32 } else { short };
         ui::set_virtual_rows(vrows);