Extract admin functionality into dedicated CommunitiesAdminPanel with a menu-based navigation system. Add ability for admins to update community avatars via the new social.coves.community.update XRPC endpoint. Changes: - Add CommunitiesAdminPanel with multi-page navigation (menu, create, profile pic) - Add updateCommunity API method with base64 image encoding - Add image_picker dependency for gallery/camera image selection - Simplify CommunitiesScreen to StatelessWidget, delegating admin to panel - Validate image size (max 1 MB) and MIME type (jpeg/png/webp) - Upgrade Gradle to 8.11.1 and Android plugin to 8.9.1 - Add current vs new avatar preview before upload Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>