Main coves client

refactor(image): extract reusable image picker components master

Extract image picking logic from communities_admin_panel into reusable components for consistent image handling across the app: - PickedImage model for typed image data (file, bytes, mimeType) - ImagePickerUtils with validation, constraints, and MIME detection - ImageSourcePicker widget for gallery/camera selection bottom sheet Also improves error handling with ImageValidationException and replaces debugPrint calls with dart:developer logging. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>