refactor(techniques): wire TechniqueRepository into techniques router replacing direct db.query() with repo pattern, domain exceptions, and UnitOfWork

backend/app/domain/entities/technique.py

@@ -46,6 +46,8 @@ class TechniqueEntity:
     status_global: TechniqueStatus = TechniqueStatus.not_evaluated
     review_required: bool = False
     last_review_date: datetime | None = None
+    mitre_version: str | None = None
+    mitre_last_modified: datetime | None = None
 
     # -- Factory -----------------------------------------------------------
 
@@ -94,6 +96,8 @@ class TechniqueEntity:
             status_global=status,
             review_required=model.review_required or False,
             last_review_date=model.last_review_date,
+            mitre_version=getattr(model, "mitre_version", None),
+            mitre_last_modified=getattr(model, "mitre_last_modified", None),
         )
 
     def apply_to(self, model: Any) -> None: