Auto-format token and join-code inputs with dashes while typing

Shared wireCodeMask helper: uppercase, dash every 4 chars, raw-length
cap, caret preserved, backspace over a dash deletes the char before it.

public/js/views/auth.js

@@ -2,7 +2,7 @@
 // Two panels: create a new account (one-time token reveal) or log in with an
 // existing account number.
 import { api } from '../api.js';
-import { el, mount, toast } from '../dom.js';
+import { el, mount, toast, wireCodeMask } from '../dom.js';
 import { groupCode, normalizeCode } from '../format.js';
 
 export function renderAuth(container, ctx) {
@@ -123,8 +123,10 @@ export function renderAuth(container, ctx) {
       autocapitalize: 'characters',
       spellcheck: 'false',
       placeholder: 'XXXX-XXXX-XXXX-XXXX',
+      maxlength: '19',
       'aria-label': 'Account number',
     });
+    wireCodeMask(input, 16);
     const submitBtn = el('button', { class: 'btn btn-primary btn-block', type: 'submit' }, 'Log in');
 
     async function onSubmit(e) {