Fix Windows overlay scaling bounds (#34)

src/core/services/overlay-window-bounds.test.ts

@@ -0,0 +1,36 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { normalizeOverlayWindowBoundsForPlatform } from './overlay-window-bounds';
+
+test('normalizeOverlayWindowBoundsForPlatform returns original geometry outside Windows', () => {
+  const geometry = { x: 150, y: 90, width: 1200, height: 675 };
+  assert.deepEqual(normalizeOverlayWindowBoundsForPlatform(geometry, 'linux', null), geometry);
+});
+
+test('normalizeOverlayWindowBoundsForPlatform converts Windows physical pixels to DIP', () => {
+  assert.deepEqual(
+    normalizeOverlayWindowBoundsForPlatform(
+      {
+        x: 150,
+        y: 75,
+        width: 1920,
+        height: 1080,
+      },
+      'win32',
+      {
+        screenToDipRect: (_window, rect) => ({
+          x: Math.round(rect.x / 1.5),
+          y: Math.round(rect.y / 1.5),
+          width: Math.round(rect.width / 1.5),
+          height: Math.round(rect.height / 1.5),
+        }),
+      },
+    ),
+    {
+      x: 100,
+      y: 50,
+      width: 1280,
+      height: 720,
+    },
+  );
+});