Fix modal event handling for ACF block version 3

[adambichler]

Restructured the event listener attachment to fix compatibility issues with blockVersion3:

• Created new attachCropModalEvents() method that attaches event listeners directly to modal buttons after they're created in the DOM
• Moved all button event logic from initialize() into this new method
• Called attachCropModalEvents() in openModal() after modal DOM is rendered
• Added proper cleanup in closeModal() to remove event listeners and prevent memory leaks
• Added null check for cropper in closeModal()

Benefits:

• More reliable - listeners attached when needed, not during init
• Better memory management with proper cleanup
• Maintains backward compatibility
• Uses namespaced event handlers (.aiarc) for clean unbinding

Notice:

• Tested within repeater fields, flexible content fields and simple field setup.
• Tested backward compatibility when not using blockVersion: 3

Fixes #154