feat: multi-material overlays, presentation guides, and release prebuilds

Align control/presentation with presentation screen rect and darkness z-order; sync window titles and session window cleanup. Pack Win/Mac/Linux with npmRebuild disabled and release-native-prep for classic-level and sharp.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/shared/geometry/fitAspectRect.ts

@@ -0,0 +1,22 @@
+/** Вписать прямоугольник целевого аспекта в бокс (как object-fit: contain). */
+export function fitAspectRect(
+  boxW: number,
+  boxH: number,
+  aspectW: number,
+  aspectH: number,
+): { x: number; y: number; w: number; h: number } {
+  const bw = Math.max(1, boxW);
+  const bh = Math.max(1, boxH);
+  const aw = Math.max(1, aspectW);
+  const ah = Math.max(1, aspectH);
+  const boxAspect = bw / bh;
+  const targetAspect = aw / ah;
+  if (boxAspect > targetAspect) {
+    const h = bh;
+    const w = h * targetAspect;
+    return { x: (bw - w) / 2, y: 0, w, h };
+  }
+  const w = bw;
+  const h = w / targetAspect;
+  return { x: 0, y: (bh - h) / 2, w, h };
+}