fix: Add @tailwindcss/postcss dependency

- Required for Tailwind CSS v4 with PostCSS
- Fixes PostCSS plugin loading error in Docker build

package-lock.json

@@ -8,11 +8,24 @@
       "name": "dealplustech-astro",
       "version": "0.0.1",
       "dependencies": {
+        "@tailwindcss/postcss": "^4.2.1",
         "@tailwindcss/vite": "^4.2.1",
         "astro": "^5.17.1",
         "tailwindcss": "^4.2.1"
       }
     },
+    "node_modules/@alloc/quick-lru": {
+      "version": "5.2.0",
+      "resolved": "https://registry.npmjs.org/@alloc/quick-lru/-/quick-lru-5.2.0.tgz",
+      "integrity": "sha512-UrcABB+4bUrFABwbluTIBErXwvbsU/V7TZWfmbgJfbkwiBuziS9gxdODUyuiecfdGQ85jglMW6juS3+z5TsKLw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=10"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/sindresorhus"
+      }
+    },
     "node_modules/@astrojs/compiler": {
       "version": "2.13.1",
       "resolved": "https://registry.npmjs.org/@astrojs/compiler/-/compiler-2.13.1.tgz",
@@ -1748,6 +1761,19 @@
         "node": ">= 20"
       }
     },
+    "node_modules/@tailwindcss/postcss": {
+      "version": "4.2.1",
+      "resolved": "https://registry.npmjs.org/@tailwindcss/postcss/-/postcss-4.2.1.tgz",
+      "integrity": "sha512-OEwGIBnXnj7zJeonOh6ZG9woofIjGrd2BORfvE5p9USYKDCZoQmfqLcfNiRWoJlRWLdNPn2IgVZuWAOM4iTYMw==",
+      "license": "MIT",
+      "dependencies": {
+        "@alloc/quick-lru": "^5.2.0",
+        "@tailwindcss/node": "4.2.1",
+        "@tailwindcss/oxide": "4.2.1",
+        "postcss": "^8.5.6",
+        "tailwindcss": "4.2.1"
+      }
+    },
     "node_modules/@tailwindcss/vite": {
       "version": "4.2.1",
       "resolved": "https://registry.npmjs.org/@tailwindcss/vite/-/vite-4.2.1.tgz",