feat: add expo mobile application source code

mobile/hooks/useForm.ts

@@ -0,0 +1,35 @@
+import { useState } from 'react';
+
+export function useForm<T>(initialValues: T) {
+  const [values, setValues] = useState<T>(initialValues);
+  const [errors, setErrors] = useState<Partial<Record<keyof T, string>>>({});
+
+  const handleChange = (name: keyof T, value: string) => {
+    setValues({
+      ...values,
+      [name]: value,
+    });
+    // Clear error when user types
+    if (errors[name]) {
+      setErrors({
+        ...errors,
+        [name]: undefined,
+      });
+    }
+  };
+
+  const setFieldError = (name: keyof T, error: string) => {
+    setErrors({
+      ...errors,
+      [name]: error,
+    });
+  };
+
+  return {
+    values,
+    errors,
+    handleChange,
+    setFieldError,
+    setValues,
+  };
+}