refactor: update company registration flow and email handling; switch to zod for validation

lib/validations/companySchema.ts

@@ -1,8 +1,16 @@
-import * as yup from "yup";
+import { z } from 'zod';
 
-export const companySchema = yup.object({
-  companyName: yup.string().required("Company name is required"),
-  contactPerson: yup.string().required("Contact person is required"),
-  email: yup.string().email("Invalid email").required("Email is required"),
-  phone: yup.string().optional(),
+export const companySchema = z.object({
+  companyName: z.string({
+    required_error: 'Company name is required',
+  }),
+  contactPerson: z.string({
+    required_error: 'Contact person is required',
+  }),
+  email: z
+    .string({
+      required_error: 'Email is required',
+    })
+    .email('Invalid email'),
+  phone: z.string().optional(),
 });