[bugfix] Fix miscellaneous issues prior to release 0.9.4

[lstein]

This pull request removes the macOS .dmg build and deployment workflow from the project and refines the grid view's image loading and event handling logic in the frontend. The most important changes are grouped below:

Build and Deployment Workflow Changes:

• Removed the .github/workflows/deploy-dmg.yml workflow and all related steps from the main deployment pipeline, so .dmg files are no longer built or released. The release process now only uploads .zip, .tar.gz, and .app artifacts. (.github/workflows/deploy-dmg.yml, .github/workflows/deploy.yml) [1] [2] [3]
• Deleted the legacy macOS setup.py used for py2app, reflecting the removal of the .dmg build process. (macos/setup.py)

Frontend Grid View Improvements:

• Improved batch image loading in grid-view.js by yielding to the UI thread every 4 images, handling transitions and errors more robustly, and preventing slide change events during batch operations for smoother user experience. (photomap/frontend/static/javascript/grid-view.js) [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]
• Updated the grid view to use thumbnail URLs instead of full image URLs for faster loading and better performance. (photomap/frontend/static/javascript/grid-view.js)

Event Handling and UI Responsiveness:

• Added better spinner management and batch loading state handling during grid navigation and resizing, ensuring UI responsiveness and preventing concurrent batch loads. (photomap/frontend/static/javascript/grid-view.js)
• Improved transition and slide change event handling to avoid unnecessary updates and UI glitches, especially during grid initialization and resizing. (photomap/frontend/static/javascript/grid-view.js) [1] [2] [3]

Additional Minor Improvements:

• Added debugging logs for swiper initialization and slide resets, and removed unnecessary console output for slide seeking. (photomap/frontend/static/javascript/swiper.js, photomap/frontend/static/javascript/slide-state.js) [1] [2] [3]
• Added a mouseleave event handler to remove UMAP thumbnails when the mouse leaves the plot area. (photomap/frontend/static/javascript/umap.js)