Add firma flag to availability and show office/home label

Server query gets the last stamp's BU_TERM in the same OUTER APPLY
as LAST_STAMP, exposing FIRMA (1 = Zeiterfassung/Büro). Three OUTER
APPLYs reduced to two by combining MAX(BU_BU) with TOP 1 ORDER BY.

Client model gains a firma boolean and the people-tile indicator
appends "· Büro" or "· Home" next to the timestamp, but only when
the user is logged in.

3CX_TAPI.user.js

@@ -859,7 +859,11 @@ class Availability {
             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>';
+        var location = '';
+        if (entry.loggedIn) {
+            location = entry.firma ? ' · Büro' : ' · Home';
+        }
+        indicator.innerHTML = '<span class="tapi-dot ' + dotClass + '"></span><small>' + time + location + '</small>';
     }
     updateSquare(square) {
         var extension = square.dataset.tapiExtension;