feat(web): scaffold Next.js 16 dashboard with design system and auth client (#82)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/web/package.json

@@ -11,11 +11,16 @@
     "start": "next start"
   },
   "dependencies": {
+    "@mosaic/design-tokens": "workspace:^",
+    "better-auth": "^1.5.5",
+    "clsx": "^2.1.0",
     "next": "^16.0.0",
     "react": "^19.0.0",
-    "react-dom": "^19.0.0"
+    "react-dom": "^19.0.0",
+    "tailwind-merge": "^3.5.0"
   },
   "devDependencies": {
+    "@tailwindcss/postcss": "^4.0.0",
     "@types/node": "^22.0.0",
     "@types/react": "^19.0.0",
     "@types/react-dom": "^19.0.0",