feat: enhance contact form with toast notifications and error handling

frontend/package-lock.json

@@ -13,6 +13,7 @@
         "next-intl": "^4.1.0",
         "react": "^19.0.0",
         "react-dom": "^19.0.0",
+        "react-hot-toast": "^2.5.2",
         "react-icons": "^5.5.0"
       },
       "devDependencies": {
@@ -2443,7 +2444,6 @@
       "version": "3.1.3",
       "resolved": "https://registry.npmjs.org/csstype/-/csstype-3.1.3.tgz",
       "integrity": "sha512-M1uQkMl8rQK/szD0LNhtqxIPLpimGm8sOBwU7lLnCpSbTyY3yeU1Vc7l4KT5zT4s/yOxHH5O7tIuuLOCnLADRw==",
-      "dev": true,
       "license": "MIT"
     },
     "node_modules/damerau-levenshtein": {
@@ -3544,6 +3544,15 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/goober": {
+      "version": "2.1.16",
+      "resolved": "https://registry.npmjs.org/goober/-/goober-2.1.16.tgz",
+      "integrity": "sha512-erjk19y1U33+XAMe1VTvIONHYoSqE4iS7BYUZfHaqeohLmnC0FdxEh7rQU+6MZ4OajItzjZFSRtVANrQwNq6/g==",
+      "license": "MIT",
+      "peerDependencies": {
+        "csstype": "^3.0.10"
+      }
+    },
     "node_modules/gopd": {
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/gopd/-/gopd-1.2.0.tgz",
@@ -5203,6 +5212,23 @@
         "react": "^19.1.0"
       }
     },
+    "node_modules/react-hot-toast": {
+      "version": "2.5.2",
+      "resolved": "https://registry.npmjs.org/react-hot-toast/-/react-hot-toast-2.5.2.tgz",
+      "integrity": "sha512-Tun3BbCxzmXXM7C+NI4qiv6lT0uwGh4oAfeJyNOjYUejTsm35mK9iCaYLGv8cBz9L5YxZLx/2ii7zsIwPtPUdw==",
+      "license": "MIT",
+      "dependencies": {
+        "csstype": "^3.1.3",
+        "goober": "^2.1.16"
+      },
+      "engines": {
+        "node": ">=10"
+      },
+      "peerDependencies": {
+        "react": ">=16",
+        "react-dom": ">=16"
+      }
+    },
     "node_modules/react-icons": {
       "version": "5.5.0",
       "resolved": "https://registry.npmjs.org/react-icons/-/react-icons-5.5.0.tgz",