feat: rename Agent label to Professional in login and signup forms

src/app/(auth)/login/page.tsx

@@ -171,7 +171,7 @@ export default function LoginPage() {
                 : 'text-[#00293d]'
             }`}
           >
-            Agent
+            Professional
           </button>
         </div>
       </div>

src/app/(auth)/signup/page.tsx

@@ -179,7 +179,7 @@ export default function SignUpPage() {
                 : 'text-[#00293d]'
             }`}
           >
-            Agent
+            Professional
           </button>
         </div>
       </div>