chore(frontend): Upgrade Next.js 14 → 15.5 and React 18 → 19

- Next.js upgraded from 14.2.0 to 15.5.4
- React upgraded from 18 to 19.2.0
- react-dom upgraded from 18 to 19.2.0

Frontend server working correctly:
- Dev server starts successfully
- Pages compile without errors
- HTTP 200 responses on all routes

Next steps:
- Fix next.config.js warning (swcMinify is deprecated)
- Upgrade MUI packages
- Upgrade testing libraries

maternal-web/tsconfig.json

@@ -1,6 +1,10 @@
 {
   "compilerOptions": {
-    "lib": ["dom", "dom.iterable", "esnext"],
+    "lib": [
+      "dom",
+      "dom.iterable",
+      "esnext"
+    ],
     "allowJs": true,
     "skipLibCheck": true,
     "strict": true,
@@ -18,9 +22,19 @@
       }
     ],
     "paths": {
-      "@/*": ["./*"]
-    }
+      "@/*": [
+        "./*"
+      ]
+    },
+    "target": "ES2017"
   },
-  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
-  "exclude": ["node_modules"]
+  "include": [
+    "next-env.d.ts",
+    "**/*.ts",
+    "**/*.tsx",
+    ".next/types/**/*.ts"
+  ],
+  "exclude": [
+    "node_modules"
+  ]
 }