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/App.tsx

@@ -2,7 +2,10 @@ import { Routes, Route, Navigate } from "react-router-dom";
 import LoginPage from "./pages/LoginPage";
 import DashboardPage from "./pages/DashboardPage";
 import TechniquesPage from "./pages/TechniquesPage";
+import TechniqueDetailPage from "./pages/TechniqueDetailPage";
 import TestsPage from "./pages/TestsPage";
+import TestCreatePage from "./pages/TestCreatePage";
+import TestDetailPage from "./pages/TestDetailPage";
 import SystemPage from "./pages/SystemPage";
 import Layout from "./components/Layout";
 import ProtectedRoute from "./components/ProtectedRoute";
@@ -23,7 +26,10 @@ export default function App() {
       >
         <Route path="/dashboard" element={<DashboardPage />} />
         <Route path="/techniques" element={<TechniquesPage />} />
+        <Route path="/techniques/:mitreId" element={<TechniqueDetailPage />} />
         <Route path="/tests" element={<TestsPage />} />
+        <Route path="/tests/new" element={<TestCreatePage />} />
+        <Route path="/tests/:testId" element={<TestDetailPage />} />
         <Route
           path="/system"
           element={