Capture at full retina resolution

The ScreenCaptureKit stream was sized in points at 1x scale, so retina
displays produced half-resolution captures that appeared pixelated.
Request backingScale x pixels and derive the crop scale from the actual
captured image dimensions.

💘 Generated with Crush

Assisted-by: Crush:deepseek-v4-flash-0731

build-app.sh

@@ -108,9 +108,9 @@ cat > "$APP/Contents/Info.plist" <<'PLIST'
     <key>CFBundleIconFile</key>
     <string>Icon</string>
     <key>CFBundleShortVersionString</key>
-    <string>1.1.1</string>
+    <string>1.1.2</string>
     <key>CFBundleVersion</key>
-    <string>11</string>
+    <string>12</string>
     <key>LSUIElement</key>
     <true/>
     <key>NSHighResolutionCapable</key>