feat: Phase 8 - Frontend main views (T-026 to T-031)

Implement all main frontend views for the MITRE ATT&CK coverage platform:

- T-026: Dashboard with coverage summary cards and tactic breakdown table

- T-027: Interactive ATT&CK matrix with filtering by status, tactic, platform

- T-028: Technique detail page with tests, intel items, and review actions

- T-029: Test creation form with technique selector and validation

- T-030: Test detail page with drag and drop evidence upload and download

- T-031: System admin panel with MITRE sync and intel scan controls

New components: CoverageSummaryCard, TacticCoverageChart, AttackMatrix, TechniqueCell, TestForm, EvidenceUpload, EvidenceList

New API modules: metrics.ts, techniques.ts, tests.ts, evidence.ts, system.ts

All views use TanStack Query for data fetching with proper loading and error states. Role-based UI controls for admin/lead actions.

frontend/src/api/tests.ts

@@ -0,0 +1,67 @@
+import client from "./client";
+import type { Test, TestResult } from "../types/models";
+
+export interface TestCreatePayload {
+  technique_id: string;
+  name: string;
+  description?: string;
+  platform?: string;
+  procedure_text?: string;
+  tool_used?: string;
+}
+
+export interface TestUpdatePayload {
+  name?: string;
+  description?: string;
+  platform?: string;
+  procedure_text?: string;
+  tool_used?: string;
+  result?: TestResult;
+}
+
+export interface TestValidatePayload {
+  result: TestResult;
+  comments?: string;
+}
+
+export interface TestWithEvidences extends Test {
+  evidences?: Array<{
+    id: string;
+    test_id: string;
+    file_name: string;
+    sha256_hash: string;
+    uploaded_by: string | null;
+    uploaded_at: string;
+    download_url?: string;
+  }>;
+}
+
+/** Create a new test. */
+export async function createTest(payload: TestCreatePayload): Promise<Test> {
+  const { data } = await client.post<Test>("/tests", payload);
+  return data;
+}
+
+/** Get test by ID with evidences. */
+export async function getTestById(testId: string): Promise<TestWithEvidences> {
+  const { data } = await client.get<TestWithEvidences>(`/tests/${testId}`);
+  return data;
+}
+
+/** Update a test (only draft/rejected). */
+export async function updateTest(testId: string, payload: TestUpdatePayload): Promise<Test> {
+  const { data } = await client.patch<Test>(`/tests/${testId}`, payload);
+  return data;
+}
+
+/** Validate a test. */
+export async function validateTest(testId: string, payload: TestValidatePayload): Promise<Test> {
+  const { data } = await client.post<Test>(`/tests/${testId}/validate`, payload);
+  return data;
+}
+
+/** Reject a test. */
+export async function rejectTest(testId: string): Promise<Test> {
+  const { data } = await client.post<Test>(`/tests/${testId}/reject`);
+  return data;
+}