build: postcss 설정

- discard-dedupe
- autoprefixer

package.json

@@ -68,16 +68,21 @@
     "@typescript-eslint/parser": "^5.8.0",
     "@vue/compiler-sfc": "^3.2.26",
     "@vue/eslint-config-typescript": "^10.0.0",
+    "autoprefixer": "^10.4.1",
     "babel-plugin-lodash": "^3.3.4",
     "babel-preset-modern-browsers": "^15.0.2",
     "bootswatch": "^5.1.3",
     "clean-terminal-webpack-plugin": "^3.0.0",
     "css-loader": "^6.5.1",
+    "cssnano": "^5.0.14",
     "esbuild-loader": "^2.18.0",
     "eslint": "^8.5.0",
     "eslint-plugin-vue": "^8.2.0",
     "file-loader": "^6.2.0",
     "mini-css-extract-plugin": "^2.4.5",
+    "postcss-discard-duplicates": "^5.0.1",
+    "postcss-import": "^14.0.2",
+    "postcss-loader": "^6.2.1",
     "pre-commit": "^1.2.2",
     "sass": "^1.45.1",
     "sass-loader": "^12.4.0",