feat: resend verification email on sign-in and improve email template

- Add `sendOnSignIn: true` to emailVerification config so unverified users
  receive a new verification email when they attempt to sign in
- Create styled verification email template matching the invoice email design
- Extract `sendVerificationEmail` helper to keep auth.ts clean
- Show friendly message on login when email is not verified

packages/server/src/verification/send-verification-email.tsx

@@ -1,4 +1,7 @@
+import { renderAsync } from "@react-email/components";
+import VerifyEmailTemplate from "../emails/emails/verify-email";
 import { sendEmailNotification } from "../utils/notifications/utils";
+
 export const sendEmail = async ({
 	email,
 	subject,
@@ -26,3 +29,25 @@ export const sendEmail = async ({
 
 	return true;
 };
+
+export const sendVerificationEmail = async ({
+	userName,
+	email,
+	verificationUrl,
+}: {
+	userName: string;
+	email: string;
+	verificationUrl: string;
+}) => {
+	const html = await renderAsync(
+		VerifyEmailTemplate({
+			userName: userName || "User",
+			verificationUrl,
+		}),
+	);
+	await sendEmail({
+		email,
+		subject: "Verify your email",
+		text: html,
+	});
+};