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/trips.js

@@ -1,6 +1,6 @@
 // Trip list dashboard: cards, a "new trip" form, and a "join a trip" form.
 import { api } from '../api.js';
-import { el, mount, clear, loading, errorBox, emptyState, toast } from '../dom.js';
+import { el, mount, clear, loading, errorBox, emptyState, toast, wireCodeMask } from '../dom.js';
 import { formatRange, ymd, parseYMD, pluralize, normalizeCode } from '../format.js';
 import { enableTripReorder } from './dragdrop.js';
 
@@ -201,8 +201,10 @@ export function renderTrips(container, ctx) {
       autocapitalize: 'characters',
       spellcheck: 'false',
       placeholder: 'XXXX-XXXX',
+      maxlength: '9',
       'aria-label': 'Join code',
     });
+    wireCodeMask(codeInput, 8);
     const errorEl = el('p', { class: 'form-error' });
     const submitBtn = el('button', { class: 'btn btn-primary', type: 'submit' }, 'Join trip');