feat(assign): let leads manually assign operators + sync Jira; send platform as Jira label

Adds GET /users/operators (leads+admin) and wires a lead-only assign
control into the test detail header, calling the existing but
previously unreachable POST /tests/{id}/assign endpoint. Manual
assignment now also pushes the Jira ticket assignee immediately
instead of waiting for the operator to start execution.

Also adds test.platform as a kebab-case label on Jira ticket creation.

backend/app/routers/tests.py

@@ -1282,18 +1282,21 @@ def assign_test_operators(
 ):
     """Assign red_tech and/or blue_tech operators to a test. Admin/leads only."""
     test = crud_get_test_or_raise(db, test_id)
+    newly_assigned: User | None = None
 
     if payload.red_tech_assignee is not None:
         u = db.query(User).filter(User.id == payload.red_tech_assignee).first()
         if not u or u.role not in ("red_tech", "red_lead", "admin"):
             raise HTTPException(status_code=400, detail="Invalid red tech assignee")
         test.red_tech_assignee = payload.red_tech_assignee
+        newly_assigned = u
 
     if payload.blue_tech_assignee is not None:
         u = db.query(User).filter(User.id == payload.blue_tech_assignee).first()
         if not u or u.role not in ("blue_tech", "blue_lead", "admin"):
             raise HTTPException(status_code=400, detail="Invalid blue tech assignee")
         test.blue_tech_assignee = payload.blue_tech_assignee
+        newly_assigned = u
 
     # Handle intentional null (clearing) — model_fields_set tracks which keys were sent
     if "red_tech_assignee" in payload.model_fields_set and payload.red_tech_assignee is None:
@@ -1307,6 +1310,15 @@ def assign_test_operators(
     })
     db.commit()
     db.refresh(test)
+
+    if newly_assigned is not None:
+        try:
+            from app.services.jira_service import push_assignee_update
+            push_assignee_update(db, test, newly_assigned)
+            db.commit()
+        except Exception:  # nosec B110
+            pass  # jira_service already logs warnings internally
+
     return test