Migrate TREK 3 to NestJS + React 19 with a shared Zod contract layer

Brownfield strangler migration of the backend onto NestJS modules
(auth, trips, days, places, assignments, packing, todo, budget,
reservations, collab, files, photos, journey, share, settings, backup,
oidc, oauth, admin, atlas, vacay, weather, airports, maps, categories,
tags, notifications, system-notices) served through a per-prefix
dispatcher, keeping the existing SQLite/better-sqlite3 DB and JWT
httpOnly cookie auth, with behavioural parity for every route.

Client: React 19 upgrade, "page = wiring container + data hook"
pattern across all pages, per-domain Zustand stores bound to
@trek/shared contracts, and decomposition of the large components
(DayPlanSidebar, PackingListPanel, CollabNotes, FileManager,
MemoriesPanel, PlacesSidebar, CollabChat, SystemNoticeModal,
BudgetPanel, PlaceFormModal, ...) into focused render units backed by
in-file hooks.

Apply the shared global request pipeline (helmet/CSP, CORS, HSTS,
forced HTTPS, the global MFA policy and request logging) to the NestJS
instance as well, so a migrated route is protected identically to the
legacy fallback rather than bypassing it.

server/tests/unit/nest/system-notices.controller.test.ts

@@ -0,0 +1,55 @@
+import { describe, it, expect, vi } from 'vitest';
+import { HttpException } from '@nestjs/common';
+import { SystemNoticesController } from '../../../src/nest/system-notices/system-notices.controller';
+import type { SystemNoticesService } from '../../../src/nest/system-notices/system-notices.service';
+import type { User } from '../../../src/types';
+import type { SystemNoticeDto } from '@trek/shared';
+
+function makeController(svc: Partial<SystemNoticesService>) {
+  return new SystemNoticesController(svc as SystemNoticesService);
+}
+
+const user = { id: 7 } as User;
+
+const notice: SystemNoticeDto = {
+  id: 'welcome', display: 'modal', severity: 'info',
+  titleKey: 'notice.welcome.title', bodyKey: 'notice.welcome.body', dismissible: true,
+};
+
+/** Run `fn`, expecting an HttpException; return its { status, body }. */
+function thrown(fn: () => unknown): { status: number; body: unknown } {
+  try {
+    fn();
+  } catch (err) {
+    expect(err).toBeInstanceOf(HttpException);
+    const e = err as HttpException;
+    return { status: e.getStatus(), body: e.getResponse() };
+  }
+  throw new Error('expected the handler to throw');
+}
+
+describe('SystemNoticesController (parity with the legacy /api/system-notices route)', () => {
+  describe('GET /active', () => {
+    it('returns the evaluated notices for the current user', () => {
+      const getActiveFor = vi.fn().mockReturnValue([notice]);
+      expect(makeController({ getActiveFor }).active(user)).toEqual([notice]);
+      expect(getActiveFor).toHaveBeenCalledWith(7);
+    });
+  });
+
+  describe('POST /:id/dismiss', () => {
+    it('returns nothing (204) when the dismiss succeeds', () => {
+      const dismiss = vi.fn().mockReturnValue(true);
+      expect(makeController({ dismiss }).dismiss(user, 'welcome')).toBeUndefined();
+      expect(dismiss).toHaveBeenCalledWith(7, 'welcome');
+    });
+
+    it('404 { error: NOTICE_NOT_FOUND } when the id is unknown', () => {
+      const dismiss = vi.fn().mockReturnValue(false);
+      expect(thrown(() => makeController({ dismiss }).dismiss(user, 'nope'))).toEqual({
+        status: 404,
+        body: { error: 'NOTICE_NOT_FOUND' },
+      });
+    });
+  });
+});