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/three/GhostCanvas.tsx

@@ -1,6 +1,7 @@
 import { useEffect, useRef } from 'react'
 import { GhostScene } from './GhostScene'
 import type { GhostMood, GhostVisualState } from './GhostScene'
+import { hauntBus } from '../lib/haunting'
 
 export type GhostCanvasProps = {
   visual: GhostVisualState | null
@@ -26,7 +27,10 @@ export function GhostCanvas({ visual, mood, getAmplitude, className }: GhostCanv
     const ampTimer = window.setInterval(() => {
       scene.setSpeakAmplitude(ampRef.current?.() ?? 0)
     }, 50)
+    // Apparition flares from the haunting layer surge the ghost.
+    const offFlare = hauntBus.on('flare', ({ strength }) => scene.flare(strength))
     return () => {
+      offFlare()
       window.clearInterval(ampTimer)
       scene.dispose()
       sceneRef.current = null

frontend/src/three/GhostScene.ts

@@ -234,6 +234,10 @@ export class GhostScene {
   private smoothedAmp = 0
   private energy = 0.15
   private disposed = false
+  private flareAmp = 0
+  private lastT = 0
+  private baseScale = 1
+  private baseOpacity = 1
 
   constructor(canvas: HTMLCanvasElement) {
     this.canvas = canvas
@@ -373,6 +377,14 @@ export class GhostScene {
     this.speakAmp = Math.max(0, Math.min(1, amp))
   }
 
+  /**
+   * Brief apparition surge (strength 0..1): brightness, scale and agitation
+   * spike, decaying back to normal over ~1.2s. Stacking flares take the max.
+   */
+  flare(strength: number): void {
+    this.flareAmp = Math.max(this.flareAmp, Math.max(0, Math.min(1, strength)))
+  }
+
   setVisual(visual: GhostVisualState | null): void {
     this.visual = visual
     if (!visual) {
@@ -391,6 +403,8 @@ export class GhostScene {
     this.wispMat.uniforms.uColor.value = hsl(visual.hue, 0.9, 0.7)
     this.wispMat.uniforms.uMoteSpeed.value = params.moteSpeed
     this.mistMat.uniforms.uColor.value = hsl(visual.hue, 0.5, 0.4)
+    this.baseScale = params.scale
+    this.baseOpacity = params.opacity
     this.ghost.scale.setScalar(params.scale)
     this.ghost.visible = true
     this.wisps.visible = true
@@ -417,24 +431,33 @@ export class GhostScene {
 
   private renderFrame(): void {
     const t = this.clock.getElapsedTime()
+    const dt = Math.min(0.1, Math.max(0, t - this.lastT))
+    this.lastT = t
 
-    // Energy target from mood; smooth toward it.
+    // Apparition surge decays linearly over ~1.2s.
+    this.flareAmp = Math.max(0, this.flareAmp - dt / 1.2)
+
+    // Energy target from mood; smooth toward it. A flare agitates on top.
     const target =
       this.mood === 'gathering' ? 0.9 : this.mood === 'attuning' ? 0.4 : this.mood === 'speaking' ? 0.55 : 0.15
     this.energy += (target - this.energy) * 0.04
     this.smoothedAmp += (this.speakAmp - this.smoothedAmp) * 0.25
+    const flaredEnergy = Math.min(1, this.energy + this.flareAmp * 0.55)
 
     const ghostU = this.ghostMat.uniforms
     ghostU.uTime.value = t
-    ghostU.uEnergy.value = this.energy
+    ghostU.uEnergy.value = flaredEnergy
     ghostU.uSpeak.value = this.smoothedAmp
+    ghostU.uOpacity.value = Math.min(1.8, this.baseOpacity * (1 + this.flareAmp * 0.9))
     this.wispMat.uniforms.uTime.value = t
-    this.wispMat.uniforms.uEnergy.value = this.energy
+    this.wispMat.uniforms.uEnergy.value = flaredEnergy
     this.wispMat.uniforms.uSpeak.value = this.smoothedAmp
+    this.wispMat.uniforms.uOpacity.value = 0.55 * (1 + this.flareAmp * 0.9)
     this.mistMat.uniforms.uTime.value = t
     this.mistMat.uniforms.uOpacity.value = this.visual ? 0.16 : 0.1
 
-    // Idle drift / slow camera wander.
+    // Idle drift / slow camera wander; the flare swells the apparition.
+    this.ghost.scale.setScalar(this.baseScale * (1 + this.flareAmp * 0.14))
     this.ghost.position.y = 0.4 + Math.sin(t * 0.6) * 0.12
     this.ghost.rotation.y = Math.sin(t * 0.23) * 0.3
     this.veil.position.y = this.ghost.position.y - 0.3