adapting content color

[ansarikhurshid786]

Summary

This PR introduces an optional feature to auto-adapt the foreground (text/icon) color of items inside LiquidGlassView based on the backdrop luminance.

• Adds a new prop: adaptiveContentColor?: boolean (default: false)
• Adds an event: onForegroundColorChange?: (color: string) => void
• On iOS 26+, the view samples the underlying content and emits a suggested color (black/white or tinted blend).
• No behavior changes unless the prop is enabled.
• On unsupported platforms, the prop is accepted but has no effect (matches existing fallback pattern).

This addresses #7 – Auto-change contained item color.

Test plan

1. Run the example app
2. Open the new screen AdaptiveContentColorExample.
3. Observe text/icons inside LiquidGlassView adapt between light/dark as the backdrop changes.
4. Toggle the adaptiveContentColor prop to compare behavior.
5. Confirm that on Android/older iOS, the prop has no effect (children use their explicit color).

[okwasniewski]

Hey, can you provide some screenshots?

I tried building the code but run into a build issue. No known class method for selector 'effectWithStyle:'