Improve CambioImage scroll dismissal behavior

[pprunty]

Problem

Currently, the CambioImage component's dismissible functionality has limitations:

• dismissible=true only works for swipe gestures on mobile devices
• Scroll dismissal only works when scrolling directly over the image, not on the overlay/backdrop
• Desktop users have limited ways to dismiss the modal besides clicking outside

Expected Behavior

The image modal should dismiss when:

• User scrolls anywhere on the page (including overlay/backdrop areas)
• Works consistently on both desktop and mobile
• Provides intuitive dismissal interaction

Current Implementation

• Located in apps/www/registry/delta-ui/delta/cambio-image.tsx
• Has basic scroll detection but limited to specific scroll targets
• Uses Cambio library's built-in dismissible prop

Proposed Solution

Implement comprehensive scroll detection that:

1. Listens for scroll events on document/window level
2. Dismisses modal on any meaningful scroll movement (e.g., >10px)
3. Works across all devices and interaction methods
4. Maintains good UX without being overly sensitive

Additional Context

• This affects user experience when viewing images in documentation
• Current workaround requires users to click outside or use specific gestures
• Should maintain existing functionality while adding broader dismissal options

Files to Modify

• apps/www/registry/delta-ui/delta/cambio-image.tsx

Acceptance Criteria

• Modal dismisses on page scroll from any location
• Works on both desktop and mobile
• Maintains existing click-to-dismiss functionality
• No conflicts with Cambio's built-in dismissible behavior
• Scroll threshold prevents accidental dismissals