Add freehand drawing and fix residual capture pixelation

The screenshot window now supports toggling a pen to draw annotations
that are flattened into copied and saved images. Captures are also
cropped with a pixel-exact CGImage.cropping instead of a CGContext
redraw, removing residual blur on retina displays.

💘 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>1.2.1</string>
+    <string>1.3.0</string>
     <key>CFBundleVersion</key>
-    <string>21</string>
+    <string>30</string>
     <key>LSUIElement</key>
     <true/>
     <key>NSHighResolutionCapable</key>