Phase 1b: React Query + Vitest on client

- @tanstack/react-query v5 with QueryClientProvider at app root
- client/src/api/queries.ts: query-key factory, hooks for tickets, ticket, audit,
  comments, users, CTI tree + cascade, plus full mutation set
  (create/update/delete ticket, add/delete comment, CTI CRUD, user CRUD)
- All page-level useEffect + useState fetching replaced:
  Dashboard, MyTickets, TicketDetail, NewTicket, admin/CTI, admin/Users
- Dashboard preserves 300ms debounced search via separate debouncedSearch state
- CTISelect cascades via useCategories / useTypes(categoryId) / useItems(typeId);
  dependent hooks disabled until parent selected
- vitest + @testing-library/react + jsdom; 6 client tests cover SeverityBadge + StatusBadge

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

client/vitest.config.ts

@@ -0,0 +1,14 @@
+/// <reference types="vitest" />
+import { defineConfig } from 'vite';
+import react from '@vitejs/plugin-react';
+
+export default defineConfig({
+  plugins: [react()],
+  test: {
+    globals: true,
+    environment: 'jsdom',
+    setupFiles: ['./src/test/setup.ts'],
+    include: ['src/**/*.{test,spec}.{ts,tsx}'],
+    css: false,
+  },
+});