Remove unused imports, fields, variables, and dead code introduced
during the RadioGroup widget migration and prior changes.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Use AssetManifest.loadFromAssetBundle instead of manually parsing the
deprecated AssetManifest.json. Fix a broken localization key reference
(queue.cameraWithIndex → queue.itemWithIndex).
Replace the standalone scripts/validate_localizations.dart with proper
flutter tests (11 tests across two groups): file integrity checks
(directory exists, en.json present, valid JSON structure, language code
file names, deep key-completeness across all locales) and t() lookup
tests (nested resolution, missing-key fallback, parameter substitution,
partial-path fallback).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
