Replaces direct usage of document.createElement('canvas') and manual context setup with the createCanvas utility across multiple utility modules. This change improves code consistency, reduces duplication, and centralizes canvas/context creation logic. Also updates notification usage in ClipboardManager to use showNotification and showInfoNotification utilities.
Extracted image upload, mask processing, notification, and preview update logic into dedicated utility modules. Updated MaskEditorIntegration and SAMDetectorIntegration to use these new utilities, reducing code duplication and improving maintainability.
