Add lastStamp to availability and show it on people tiles

Server query extended with MAX(BU_BU) per user as LAST_STAMP,
exposed via the Availability model. Client formats it as
DD.MM. HH:mm next to the loggedIn dot, replacing the mocked time.

3CX_TAPI.user.js

@@ -853,8 +853,13 @@ class Availability {
             return;
         }
         var dotClass = entry.loggedIn ? 'tapi-dot-on' : 'tapi-dot-off';
-        var mockedTime = '13.04. 08:30';
-        indicator.innerHTML = '<span class="tapi-dot ' + dotClass + '"></span><small>' + mockedTime + '</small>';
+        var time = '';
+        if (entry.lastStamp) {
+            var d = new Date(entry.lastStamp);
+            var pad = (n) => n.toString().padStart(2, '0');
+            time = pad(d.getDate()) + '.' + pad(d.getMonth() + 1) + '. ' + pad(d.getHours()) + ':' + pad(d.getMinutes());
+        }
+        indicator.innerHTML = '<span class="tapi-dot ' + dotClass + '"></span><small>' + time + '</small>';
     }
     updateSquare(square) {
         var extension = square.dataset.tapiExtension;