Add EMF field mode, Armory shop/waitlist, and ambient haunting layer

Three self-contained features, verified complete and cross-wired
end-to-end (audited: backend 54/54 tests, frontend 110/110 tests,
tsc --noEmit clean, i18n coverage script clean):

- EMF mode: DeviceMotion/DeviceOrientation-based field-meter sensing,
  a fifth séance channel alongside Wire/EVP/Radio/Ouija, with its own
  fragment prompt persona and full frontend gauge UI.
- Armory (shop/waitlist): pre-order capture page for the future
  Ultimate Quantum Box hardware line, rate-limited public endpoint,
  explicitly no payment collection.
- Haunting layer: ambient possession effects (dread-bed audio, title
  glitching, idle-paced whispers/manifests), respects
  prefers-reduced-motion, mounted once at the app root.

Plus WebUSB robustness fixes in lib/sdr.ts (Terratec vendor ID,
explicit selectConfiguration, isSecureContext gate).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013PphXq1s43DNRj1uWKGXof

frontend/src/App.tsx

@@ -3,11 +3,13 @@
 
 import { BrowserRouter, Route, Routes } from 'react-router-dom'
 import { AuthProvider } from './state/auth'
+import { HauntingLayer } from './components/HauntingLayer'
 import { CodexEntityPage } from './pages/CodexEntityPage'
 import { CodexPage } from './pages/CodexPage'
 import { EnterPage } from './pages/EnterPage'
 import { LandingPage } from './pages/LandingPage'
 import { SeancePage } from './pages/SeancePage'
+import { ShopPage } from './pages/ShopPage'
 
 function App() {
   return (
@@ -17,12 +19,14 @@ function App() {
           <div className="crt-scanlines" />
           <div className="crt-vignette" />
         </div>
+        <HauntingLayer />
         <Routes>
           <Route path="/" element={<LandingPage />} />
           <Route path="/enter" element={<EnterPage />} />
           <Route path="/seance" element={<SeancePage />} />
           <Route path="/codex" element={<CodexPage />} />
           <Route path="/codex/:id" element={<CodexEntityPage />} />
+          <Route path="/shop" element={<ShopPage />} />
           <Route path="*" element={<LandingPage />} />
         </Routes>
       </BrowserRouter>