fix(build): migrate to @tailwindcss/vite and remove conflicting postcss config

web/package-lock.json

@@ -21,6 +21,7 @@
       "devDependencies": {
         "@eslint/js": "^9.39.1",
         "@tailwindcss/postcss": "^4.1.18",
+        "@tailwindcss/vite": "^4.1.18",
         "@types/node": "^24.10.1",
         "@types/react": "^19.2.5",
         "@types/react-dom": "^19.2.3",
@@ -2143,6 +2144,21 @@
         "tailwindcss": "4.1.18"
       }
     },
+    "node_modules/@tailwindcss/vite": {
+      "version": "4.1.18",
+      "resolved": "https://registry.npmjs.org/@tailwindcss/vite/-/vite-4.1.18.tgz",
+      "integrity": "sha512-jVA+/UpKL1vRLg6Hkao5jldawNmRo7mQYrZtNHMIVpLfLhDml5nMRUo/8MwoX2vNXvnaXNNMedrMfMugAVX1nA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@tailwindcss/node": "4.1.18",
+        "@tailwindcss/oxide": "4.1.18",
+        "tailwindcss": "4.1.18"
+      },
+      "peerDependencies": {
+        "vite": "^5.2.0 || ^6 || ^7"
+      }
+    },
     "node_modules/@tanstack/query-core": {
       "version": "5.90.20",
       "resolved": "https://registry.npmjs.org/@tanstack/query-core/-/query-core-5.90.20.tgz",