fix: add utf8 email validation support (#6239)

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

packages/validation/src/form/i18n.spec.ts

@@ -4,6 +4,7 @@ import { z } from "zod/v4";
 import type { TranslationFunction } from "@homarr/translation";
 
 import { createCustomErrorParams, zodErrorMap } from "./i18n";
+import { utf8EmailSchema } from "../email";
 
 const expectError = (error: z.core.$ZodIssue, key: string) => {
   expect(error.message).toContain(key);
@@ -111,4 +112,19 @@ describe("i18n", () => {
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     expectError(result.error.issues[0]!, "boardAlreadyExists");
   });
+
+  test("should validate UTF8SMTP email with umlauts", () => {
+    const result = utf8EmailSchema.safeParse("jörg@example.com");
+    expect(result.success).toBe(true);
+  });
+
+  test("should validate UTF8SMTP email with unicode domain", () => {
+    const result = utf8EmailSchema.safeParse("user@münchen.de");
+    expect(result.success).toBe(true);
+  });
+
+  test("should validate standard ASCII emails", () => {
+    const result = utf8EmailSchema.safeParse("user@example.com");
+    expect(result.success).toBe(true);
+  });
 });