Auto derived format

src/dto.rs

@@ -25,6 +25,9 @@ pub struct ParamDeclarationDto {
     pub kind: MetricPrimitiveKind,
     /// See `crate::data_value::ParamDeclaration::elapsed_since_last`.
     pub elapsed_since_last: bool,
+    /// See `crate::data_value::ParamDeclaration::auto_derived`. The frontend uses this to disable
+    /// editing — `POST /api/params` also rejects a request naming an auto-derived param.
+    pub auto_derived: bool,
 }
 
 #[derive(Debug, Clone, Serialize)]