feat: bottom sheet dynamic resizing

[isekovanic]

🎯 Goal

This PR refines dynamic bottom sheet sizing and cleans up a few related UI issues in the SDK and SampleApp.

• Adds content driven initial sizing to BottomSheetModal while keeping the top snap available (this is toggleable by a flag and will assume height as the maximum height the sheet can grow to through dynamic sizing)
• Moves dynamic sizing calculations to shared values
• Adds test coverage for the new bottom sheet snap point utilities
• Fixes channel preview spacing for very long channel names
• Hides quoted replies for attachment action previews such as ephemeral Giphys
• Preserves the correct standalone message shell styling for ephemeral Giphy previews
• Moves hasAttachmentActions into MessageContext so it is computed once and reused downstream

On the SampleApp side, it fixes a few visual inconsistencies:

• network/loading and DM button backgrounds now match the header
• grouped ChannelAvatar now respects the requested size
• group channel details now actually request 2xl
• GoBack and GoForward chevrons now mirror internally in RTL as an SVG PoC

🛠 Implementation details

🎨 UI Changes

iOS

Before	After

Android

Before	After

🧪 Testing

☑️ Checklist

• I have signed the Stream CLA (required)
• PR targets the develop branch
• Documentation is updated
• New code is tested in main example apps, including all possible scenarios
  • SampleApp iOS and Android
  • Expo iOS and Android

[Stream-SDK-Bot]

SDK Size

title	develop	branch	diff	status
js_bundle_size	351 KB	351 KB	0 B	🟢