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/i18n/index.ts

@@ -0,0 +1,38 @@
+import i18n from 'i18next'
+import { initReactI18next } from 'react-i18next'
+import en from './en.json'
+import es from './es.json'
+import type { Language } from '../lib/types'
+
+const STORAGE_KEY = 'qm_language'
+
+export function storedLanguage(): Language {
+  try {
+    const v = localStorage.getItem(STORAGE_KEY)
+    if (v === 'es' || v === 'en') return v
+  } catch {
+    /* private mode etc. */
+  }
+  return 'en'
+}
+
+export function persistLanguage(lang: Language): void {
+  try {
+    localStorage.setItem(STORAGE_KEY, lang)
+  } catch {
+    /* ignore */
+  }
+}
+
+void i18n.use(initReactI18next).init({
+  resources: {
+    en: { translation: en },
+    es: { translation: es },
+  },
+  lng: storedLanguage(),
+  fallbackLng: 'en',
+  interpolation: { escapeValue: false },
+  returnEmptyString: false,
+})
+
+export default i18n