fix: missing Tailwind dependency for Solid

The Solid environment was missing a dependency.

Author: crisbeto

examples/environments/solid/project/package-lock.json

@@ -7,6 +7,7 @@
   },
   "dependencies": {
     "@solidjs/start": "^1.1.0",
+    "@tailwindcss/postcss": "^4.1.13",
     "@tailwindcss/vite": "^4.1.13",
     "postcss": "^8.5.6",
     "solid-js": "^1.9.5",