level edit test:

1. Load the extension: chrome://extensions/ -> Enable Developer Mode -> Load Unpacked -> select ~/CODE/sprite-picker/
2. Start level editor: cd ~/CODE/2019-es7 && npx serve --no-clipboard . then open http://localhost:3000/level-editor.html
3. Browse sprites: Navigate to spriters-resource.com, click the green + button (bottom-right) to enter pick mode
4. Detect: Click any sprite sheet image -- red bounding boxes appear around detected sprites
5. Select: Click sprites to toggle selection (green = selected)
6. Send: Choose atlas + mode in the panel, click "Send to Level Editor" -- the Atlas Manager opens with your sprites