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

backend/app/main.py

@@ -10,6 +10,7 @@ from app.config import settings
 from app.db import Base, engine
 from app.routes.auth import router as auth_router
 from app.routes.codex import router as codex_router
+from app.routes.shop import router as shop_router
 from app.ws import AUDIO_DIR
 from app.ws import router as ws_router
 
@@ -27,6 +28,7 @@ async def lifespan(app: FastAPI):
 app = FastAPI(title="Quantumancy", lifespan=lifespan)
 app.include_router(auth_router)
 app.include_router(codex_router)
+app.include_router(shop_router)
 app.include_router(ws_router)