fix: back button alignment, mock bind flow, and timezone bug

- nav-back: add text-align:left to override page-header's center
- ble-connect mock: call bind API first to get fresh token before
  confirm, instead of relying on potentially stale URL params
- utils.js: use local time instead of UTC for toMysqlDate, fixing
  timezone mismatch with MySQL NOW() that caused bind tokens to
  appear immediately expired

server/src/lib/utils.js

@@ -2,7 +2,8 @@ function toMysqlDate(value) {
   if (!value) return null
   const d = new Date(value)
   if (Number.isNaN(d.getTime())) return null
-  return d.toISOString().slice(0, 19).replace('T', ' ')
+  const pad = n => String(n).padStart(2, '0')
+  return d.getFullYear() + '-' + pad(d.getMonth() + 1) + '-' + pad(d.getDate()) + ' ' + pad(d.getHours()) + ':' + pad(d.getMinutes()) + ':' + pad(d.getSeconds())
 }
 
 function formatDate(date) {