fix: iOS Safari uyumluluk - CSS nesting düzleştirildi

- PostCSS tabanlı build'e geçildi (@tailwindcss/postcss + postcss-preset-env)
- CSS native nesting (&) düzleştirilerek eski Safari desteği sağlandı
- iOS 15+ ve Safari 15+ desteği eklendi

frontend/.gitignore

@@ -0,0 +1 @@
+node_modules/

frontend/package.json

@@ -10,8 +10,11 @@
   "author": "",
   "license": "ISC",
   "devDependencies": {
+    "@tailwindcss/postcss": "^4.1.18",
     "autoprefixer": "^10.4.23",
     "postcss": "^8.5.6",
+    "postcss-cli": "^11.0.1",
+    "postcss-preset-env": "^11.1.3",
     "tailwindcss": "^4.1.18"
   },
   "dependencies": {

frontend/postcss.config.cjs

@@ -0,0 +1,15 @@
+module.exports = {
+    plugins: {
+        "@tailwindcss/postcss": {},
+        "postcss-preset-env": {
+            features: {
+                "nesting-rules": true,
+            },
+            browsers: [
+                "last 2 versions",
+                "iOS >= 15",
+                "Safari >= 15",
+            ],
+        },
+    },
+};