feat(manager): pairing QR carries the server's TLS key pin (&k=)

The native app refuses a server whose key differs from the QR, then talks
to it encrypted on :8443.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

manager_dashboard/src/pages/Settings/tabs/AppInfoTab.jsx

@@ -435,7 +435,7 @@ function LanAccessSection({ status, onShowQr }) {
               <span className="font-medium text-gray-800 text-xs font-mono break-all">http://{ip}</span>
               <button
                 onClick={() => onShowQr({
-                  url: waiterPairUrl(ip, status?.site_id),
+                  url: waiterPairUrl(ip, status?.site_id, status?.tls?.spki_sha256),
                   caption: 'Σαρώστε με την κάμερα του κινητού — ανοίγει την εφαρμογή σερβιτόρου. Το κινητό πρέπει να είναι στο ίδιο WiFi.',
                 })}
                 className={SMALL_BTN}
@@ -454,8 +454,14 @@ function LanAccessSection({ status, onShowQr }) {
 
 // Pairing URL: opens the waiter app when scanned with the phone camera, and the
 // native app reads the same code (?pair=<site_id>) to pair with this venue.
-function waiterPairUrl(lanIp, siteId) {
+// k = the server's TLS public-key pin: the app refuses a server whose key
-  return `http://${lanIp}/` + (siteId ? `?pair=${encodeURIComponent(siteId)}` : '')
+// differs, then talks to it encrypted on :8443 (plan step 7).
+function waiterPairUrl(lanIp, siteId, spki) {
+  const params = new URLSearchParams()
+  if (siteId) params.set('pair', siteId)
+  if (siteId && spki) params.set('k', spki)
+  const query = params.toString()
+  return `http://${lanIp}/` + (query ? `?${query}` : '')
 }
 
 function formatUptime(seconds) {