feat: add PWA — mobile multi-model chat app (Vite + React)

- Vite + React + TypeScript + Tailwind v4
- vite-plugin-pwa for service worker and manifest
- Dark mode, borderless design with glow effects
- Reuses Elec components, adapted for mobile viewport
- Standalone-ready: can install to phone home screen

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

PWA/package.json

@@ -0,0 +1,30 @@
+{
+  "name": "elec-pwa",
+  "private": true,
+  "version": "0.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "tsc && vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "react": "^19.2.5",
+    "react-dom": "^19.2.5"
+  },
+  "devDependencies": {
+    "@tailwindcss/postcss": "^4.3.0",
+    "@types/react": "^19.2.14",
+    "@types/react-dom": "^19.2.3",
+    "@vitejs/plugin-react": "^4.7.0",
+    "autoprefixer": "^10.5.0",
+    "clsx": "^2.1.1",
+    "lucide-react": "^1.11.0",
+    "postcss": "^8.5.12",
+    "tailwind-merge": "^3.5.0",
+    "tailwindcss": "^4.2.4",
+    "typescript": "~6.0.2",
+    "vite": "^6.0.0",
+    "vite-plugin-pwa": "^0.21.0"
+  }
+}