[REF] refactor file pool model and imports

- Refactor SnFilePool using freezed + sealed for consistency with other Sn models
- Add extension method listFromResponse for PoolService compatibility
- Update PoolService and utils to use SnFilePool
- Replace relative imports (../) with package imports for clarity and maintainability

Signed-off-by: Texas0295 <kimura@texas0295.top>

lib/screens/auth/captcha.config.g.dart

@@ -6,7 +6,7 @@ part of 'captcha.config.dart';
 // RiverpodGenerator
 // **************************************************************************
 
-String _$captchaUrlHash() => r'bbed0d18272dd205069642b3c6583ea2eef735d1';
+String _$captchaUrlHash() => r'd46bc43032cef504547cd528a40c23cf76f27cc8';
 
 /// See also [captchaUrl].
 @ProviderFor(captchaUrl)