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.

frontend/src/pages/TestDetailPage.tsx

@@ -23,9 +23,11 @@ import {
   holdTest,
   resumeTest,
   updateTestClassification,
+  assignTestOperators,
   getTestTimeline,
   getRetestChain,
 } from "../api/tests";
+import { getOperators } from "../api/users";
 import { uploadEvidence, getEvidence } from "../api/evidence";
 import { useAuth } from "../context/AuthContext";
 import type { TestResult, ContainmentResult, AttackSuccessResult, DataClassification, TeamSide, TestTimelineEntry } from "../types/models";
@@ -133,6 +135,14 @@ export default function TestDetailPage() {
     enabled: !!testId && !!test && (test.retest_of !== null || test.retest_count > 0),
   });
 
+  const canAssignOperators = ["red_lead", "blue_lead", "admin"].includes(user?.role ?? "");
+  const { data: operators = [] } = useQuery({
+    queryKey: ["operators"],
+    queryFn: getOperators,
+    enabled: canAssignOperators,
+    staleTime: 5 * 60 * 1000,
+  });
+
   // Hydrate drafts from test data
   useEffect(() => {
     if (test) {
@@ -368,6 +378,16 @@ export default function TestDetailPage() {
     onError: (err: unknown) => showToast(extractError(err), "error"),
   });
 
+  const assignOperatorMutation = useMutation({
+    mutationFn: ({ side, userId }: { side: "red" | "blue"; userId: string | null }) =>
+      assignTestOperators(testId!, side === "red" ? { red_tech_assignee: userId } : { blue_tech_assignee: userId }),
+    onSuccess: () => {
+      invalidateAll();
+      showToast("Assignment updated", "success");
+    },
+    onError: (err: unknown) => showToast(extractError(err), "error"),
+  });
+
   // Evidence upload
   const uploadMutation = useMutation({
     mutationFn: ({ file, team }: { file: File; team: TeamSide }) =>
@@ -532,6 +552,9 @@ export default function TestDetailPage() {
         isTogglingHold={holdMutation.isPending || resumeHoldMutation.isPending}
         onUpdateClassification={(value) => updateClassificationMutation.mutate(value)}
         isUpdatingClassification={updateClassificationMutation.isPending}
+        operators={operators}
+        onAssignOperator={(side, userId) => assignOperatorMutation.mutate({ side, userId })}
+        isAssigningOperator={assignOperatorMutation.isPending}
       />
 
       {/* Content: Tabs + Sidebar */}