Improve global statistics widget

android/gradle.properties

assets/translations/en.json

assets/translations/fr.json

fastlane/metadata/android/en-US/changelogs/6.txt

fastlane/metadata/android/fr-FR/changelogs/6.txt

lib/models/statistics.dart

lib/ui/screens/main_screen.dart

lib/ui/widgets/main_screen/statistics.dart

lib/ui/widgets/main_screen/statistics_card.dart

lib/ui/widgets/main_screen/statistics_content.dart

pubspec.yaml