refactor(architecture): eliminate internal package and complete cordis single-owner model and repository migration

- Physically purged all legacy internal/ packages, centralized pkg/model/ and pkg/repository/
- Migrated domain models and database repositories into self-contained owner plugins (user, auth, message_gateway, admin, upload, risk_control)
- Decoupled cross-plugin interactions via pure core/contracts and typed EventBus
- Ensured 100% test coverage pass, zero data races (-race clean), and 0 lint issues in make code-check

plugins/domain/upload/util/media.go

@@ -41,9 +41,10 @@ func IsDocumentExtension(ext string) bool {
 
 // NormalizeImageQuality normalizes the requested image quality query parameter.
 func NormalizeImageQuality(quality string) string {
-	switch strings.ToLower(quality) {
+	q := strings.TrimSpace(strings.ToLower(quality))
+	switch q {
 	case shared.ImageQualityLow, shared.ImageQualityMedium, shared.ImageQualityHigh:
-		return strings.ToLower(quality)
+		return q
 	default:
 		return shared.ImageQualityOrigin
 	}