feat(labs): add a hidden flag to the biomarker catalog

Add a `hidden` boolean to the Biomarker model (migration
0195_biomarker_hidden) so a marker the user no longer needs can be
soft-removed instead of deleted: it leaves the active catalog and the
lab-entry pickers but keeps its readings and canonical unit/range.

Thread `hidden` through the DTO, the update schema, the PUT handler
(field-by-field), and the list endpoint (visible markers first). Regen
the OpenAPI contract.

src/components/labs/types.ts

@@ -42,6 +42,8 @@ export interface BiomarkerDto {
   panel: string | null;
   hasContext: boolean;
   context: string | null;
+  /** v1.22 — a hidden marker drops from the active list + lab-entry pickers. */
+  hidden: boolean;
   createdAt: string;
   updatedAt: string;
 }