chore: remove postcss (#18831)

web/package.json

@@ -64,7 +64,6 @@
     "@sveltejs/enhanced-img": "^0.6.0",
     "@sveltejs/kit": "^2.15.2",
     "@sveltejs/vite-plugin-svelte": "^5.0.3",
-    "@tailwindcss/postcss": "^4.1.7",
     "@tailwindcss/vite": "^4.1.7",
     "@testing-library/jest-dom": "^6.4.2",
     "@testing-library/svelte": "^5.2.8",
@@ -85,7 +84,6 @@
     "eslint-plugin-unicorn": "^57.0.0",
     "factory.ts": "^1.4.1",
     "globals": "^16.0.0",
-    "postcss": "^8.5.0",
     "prettier": "^3.4.2",
     "prettier-plugin-organize-imports": "^4.0.0",
     "prettier-plugin-sort-json": "^4.1.1",