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/components/GraphView.tsx

@@ -43,7 +43,7 @@ export function adaptiveMax(values: number[], floor: number): number {
   return max * 1.15
 }
 
-/** Marker color per anomaly source: wire green, evp violet, radio orange. */
+/** Marker color per anomaly source: wire green, evp violet, radio orange, emf amber. */
 export function anomalyColor(source: AnomalyEntry['source']): string {
   switch (source) {
     case 'wire':
@@ -52,6 +52,8 @@ export function anomalyColor(source: AnomalyEntry['source']): string {
       return '#b26bff'
     case 'radio':
       return '#ff9d4a'
+    case 'emf':
+      return '#ffd24a'
   }
 }