feat: complete Quantumancy web app — full frontend + docs

Frontend (React 18 + TS + Vite):
- Landing: glitching hero, live /api/stats veil ticker, mode cards, featured spirits
- Séance: three.js shader ghost (hue/form per entity, mood + audio-reactive),
  Ouija planchette board spelling utterances, transcript with TTS replay,
  entity dossier, direct contact streaming, passive/active listening
- Modes: Wire Ghost telemetry panel, EVP mic anomaly detection, WebUSB
  RTL-SDR sweep + waterfall (hardware pass pending), Ouija/Direct Contact
- Codex: public registry + entity dossiers, rarity tiers, i18n EN/ES complete
- State: VeilSocket (reconnect/backoff), seance reducer, auth context
- 72 vitest tests green; served by FastAPI at :7777

Docs: README + as-built plans 3-7

frontend/src/types/webusb.d.ts

@@ -0,0 +1,77 @@
+// Minimal WebUSB ambient declarations — just the surface src/lib/sdr.ts uses.
+// WebUSB is not part of TS's dom lib and @types/web doesn't carry it.
+
+interface USBEndpoint {
+  endpointNumber: number
+  direction: 'in' | 'out'
+  type: 'bulk' | 'interrupt' | 'isochronous'
+  packetSize: number
+}
+
+interface USBAlternateInterface {
+  alternateSetting: number
+  interfaceClass: number
+  interfaceSubclass: number
+  interfaceProtocol: number
+  interfaceName?: string
+  endpoints: USBEndpoint[]
+}
+
+interface USBInterface {
+  interfaceNumber: number
+  alternates: USBAlternateInterface[]
+  claimed: boolean
+}
+
+interface USBConfiguration {
+  configurationValue: number
+  configurationName?: string
+  interfaces: USBInterface[]
+}
+
+interface USBDevice {
+  readonly opened: boolean
+  readonly configuration: USBConfiguration | null
+  open(): Promise<void>
+  close(): Promise<void>
+  claimInterface(interfaceNumber: number): Promise<void>
+  releaseInterface(interfaceNumber: number): Promise<void>
+  selectAlternateInterface(
+    interfaceNumber: number,
+    alternateSetting: number,
+  ): Promise<void>
+  controlTransferOut(
+    setup: {
+      requestType: 'standard' | 'class' | 'vendor'
+      recipient: 'device' | 'interface' | 'endpoint' | 'other'
+      request: number
+      value: number
+      index: number
+    },
+    data?: BufferSource,
+  ): Promise<USBOutTransferResult>
+  transferIn(
+    endpointNumber: number,
+    length: number,
+  ): Promise<USBInTransferResult>
+}
+
+interface USBInTransferResult {
+  data?: DataView
+  status: 'ok' | 'stall' | 'babble'
+}
+
+interface USBOutTransferResult {
+  bytesWritten: number
+  status: 'ok' | 'stall'
+}
+
+interface USB {
+  requestDevice(options: {
+    filters: Array<{ vendorId?: number; productId?: number }>
+  }): Promise<USBDevice>
+}
+
+interface Navigator {
+  readonly usb: USB
+}