Flutter: Example app with camera and live filters

[enzoftware]

Description

Build a Flutter example app that demonstrates silvestre's capabilities with camera input and live filter preview.

Tasks

• Create silvestre-flutter/example/ Flutter app
• Image picker: load from gallery or take photo with camera
• Filter selection UI: grid or list of available filters
• Real-time filter preview on selected image
• Save processed image to gallery
• Before/after comparison slider
• Filter parameter adjustment (sliders for sigma, threshold, etc.)

Acceptance Criteria

• App builds and runs on Android and iOS
• User can pick an image from gallery
• User can take a photo with camera
• All silvestre filters are available and produce visible results
• Filter application is fast enough for interactive use (< 500ms for common filters on typical phone photos)
• Processed image can be saved
• App demonstrates the Dart API patterns documented in the package