fix: add ReportContent variant to VersionContent enum

- Add ReportContent(String) variant to handle report version history
- Reports store content as plain strings unlike metrics/dashboards which use YAML
- Fixes deserialization error when fetching reports with version history

apps/api/libs/database/src/types/version_history.rs

@@ -35,6 +35,8 @@ pub enum VersionContent {
     MetricYml(Box<MetricYml>),
     #[serde(alias = "dashboard_yml")]
     DashboardYml(DashboardYml),
+    // For report files that store content as a plain string
+    ReportContent(String),
 }
 
 impl From<MetricYml> for VersionContent {