fix: add utf8 email validation support (#6239)

Co-authored-by: Thomas <thomas@ajnart.fr>

packages/validation/src/email.ts

@@ -0,0 +1,16 @@
+import { z } from "zod/v4";
+
+export const utf8EmailSchema = z.email({ pattern: z.regexes.unicodeEmail });
+
+export const optionalEmailSchema = utf8EmailSchema.or(z.string().length(0)).optional();
+
+export const nullableEmailSchema = utf8EmailSchema
+  .or(z.literal(""))
+  .transform((value) => (value === "" ? null : value))
+  .optional()
+  .nullable();
+
+export const requiredNullableEmailSchema = utf8EmailSchema
+  .or(z.literal(""))
+  .transform((value) => (value === "" ? null : value))
+  .nullable();