feat(rt-import): import Red Team engagement results as validated tests

Backend — POST /tests/import-rt (red_lead + admin):
  Accepts engagement JSON with name/date/description/operator and
  a list of techniques each with mitre_id, result, attack_success,
  platform, notes. Creates one Test per technique directly in
  'validated' state (red + blue validation = approved) bypassing
  the normal workflow. Recalculates technique.status_global for
  all affected techniques. Returns created/skipped summary.

Frontend — /tests/import-rt (new dedicated page):
  - Format reference panel (collapsible) with field descriptions
  - Download template JSON button (generates a filled example)
  - Paste JSON textarea + file upload (.json)
  - Live validation + preview table showing what will be imported
  - Import button with spinner
  - Success / warning / error result display
  Accessible to admin and red_lead only.
  Added to sidebar under Tests > Import RT Results.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/api/tests.ts

@@ -282,6 +282,38 @@ export interface TempoSyncResult {
   detail?: string;
 }
 
+// ── RT Import ──────────────────────────────────────────────────────
+
+export interface RTTechniqueEntry {
+  mitre_id: string;
+  result: "detected" | "not_detected" | "partially_detected";
+  attack_success: boolean;
+  platform?: string;
+  notes?: string;
+}
+
+export interface RTImportPayload {
+  name: string;
+  date?: string;
+  description?: string;
+  operator?: string;
+  techniques: RTTechniqueEntry[];
+}
+
+export interface RTImportResult {
+  created: number;
+  skipped: number;
+  items: { mitre_id: string; test_name: string; result: string; attack_success: boolean }[];
+  warnings: { mitre_id: string; reason: string }[];
+  engagement: string;
+}
+
+/** Import results from a real Red Team engagement. */
+export async function importRT(payload: RTImportPayload): Promise<RTImportResult> {
+  const { data } = await client.post<RTImportResult>("/tests/import-rt", payload);
+  return data;
+}
+
 /** Manually push this test's red team execution worklog to Tempo. */
 export async function syncTestToTempo(
   testId: string,