fix(users): edit profile username not lowercase (#2279)

packages/validation/src/user.ts

@@ -7,7 +7,8 @@ import type { TranslationObject } from "@homarr/translation";
 import { zodEnumFromArray } from "./enums";
 import { createCustomErrorParams } from "./form/i18n";
 
-const usernameSchema = z.string().min(3).max(255);
+// We always want the lowercase version of the username to compare it in a case-insensitive way
+const usernameSchema = z.string().trim().toLowerCase().min(3).max(255);
 
 const regexCheck = (regex: RegExp) => (value: string) => regex.test(value);
 export const passwordRequirements = [