🔄 ci(release): refactor APK release workflow with improved naming and notes

Streamline the GitHub Actions release workflow with cleaner step names,
simplified APK filenames, and enhanced release notes generation.

Changes:
- Use emoji prefixes in step names for better visibility
- Simplify APK naming convention (removed build number/SHA from filenames)
- Improve release notes with categorized changelog (Features, Fixes, Improvements)
- Add download guide with architecture recommendations
- Better tag handling for duplicate releases
- Cleaner, more maintainable workflow structure

♻️ refactor: remove unused imports and cleanup code

Remove unnecessary imports and whitespace to improve code cleanliness.

Changes:
- Remove unused imports in routing_repository.dart (connectivity_status, haversine, osrm)
- Remove unused imports in routing_service_manager.dart (haversine, osrm)
- Clean up whitespace and formatting in main_screen_controller.dart
- Reformat test file for consistent code style

📦 assets: update app icons with new sizes

Refreshed all app icon sizes for improved visual consistency across devices.

Author: MasuRii