feature: leadingImageFit on list items

[SRWieZ]

What's wrong

A list item's leading image always fills its square and crops whatever doesn't fit. That's fine for photos, but a wide picture or a logo loses its edges.

What this does

A new opt-in leadingImageFit="contain" shows the whole image inside the square instead of cropping it. The default stays as it is today (fill and crop), so existing lists don't change. It reuses the image loading from #56 and only passes the fit along. iOS and Android.

How to reproduce

The same wide image twice.

• Item A: cropped, as today.
• Item B: shown whole.

// routes/mobile.php
Route::native('/repro/leading-image-fit', \App\NativeComponents\LeadingImageFit::class);

// app/NativeComponents/LeadingImageFit.php
namespace App\NativeComponents;

use Illuminate\View\View;
use Native\Mobile\Edge\NativeComponent;

class LeadingImageFit extends NativeComponent
{
    public function render(): View
    {
        return view('native.leading-image-fit');
    }
}

{{-- resources/views/native/leading-image-fit.blade.php --}}
<native:column class="w-full h-full bg-zinc-100">
    <native:top-bar title="Leading images" />
    <native:list>
        <native:list-item headline="Item A" supporting="default (cover)" leadingImage="https://picsum.photos/id/10/400/120" />
        <native:list-item headline="Item B" supporting="contain" leadingImage="https://picsum.photos/id/10/400/120" leadingImageFit="contain" />
    </native:list>
</native:column>