feat(infra): add repository implementations, mappers, FastAPI wiring, and technique indexes

backend/app/dependencies/repositories.py

@@ -0,0 +1,30 @@
+"""FastAPI dependency providers for repositories.
+
+Wiring lives ONLY in the presentation layer — use cases and services
+never know which concrete repository implementation they receive.
+"""
+
+from fastapi import Depends
+from sqlalchemy.orm import Session
+
+from app.database import get_db
+from app.infrastructure.persistence.repositories.sa_technique_repository import (
+    SATechniqueRepository,
+)
+from app.infrastructure.persistence.repositories.sa_test_repository import (
+    SATestRepository,
+)
+
+
+def get_technique_repository(
+    db: Session = Depends(get_db),
+) -> SATechniqueRepository:
+    """Provide a TechniqueRepository backed by the current DB session."""
+    return SATechniqueRepository(db)
+
+
+def get_test_repository(
+    db: Session = Depends(get_db),
+) -> SATestRepository:
+    """Provide a TestRepository backed by the current DB session."""
+    return SATestRepository(db)