fix web TX spectrum position in CTUN mode

Add 'dup' field to state JSON (FDisplayDuplex). In CTUN+non-DUP TX,
use vfo_a_hz as spectrum center so the TX signal renders at the VFO
position instead of the display center. In CTUN+DUP TX, keep center_hz
so the RX spectrum stays correctly positioned at the filter.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

WebPageHtml.pas

@@ -410,7 +410,9 @@ begin
     'Object.keys(msg).forEach(function(k){var pk=PEND_MAP[k];if(!pk||!isPending(pk))cur[k]=msg[k];});' +
     // Обновляем localCenter/localSpan из сервера только когда пользователь не тянет
     'if(!dragging&&Date.now()-wheelActiveTs>300){' +
-    'if(msg.center_hz!=null)localCenter=msg.center_hz;' +
+    // В CTUN без DUP: TX-спектр WDSP центрирован по vfo_a_hz, а не по DDC LO.
+    // В CTUN с DUP: показываем RX-спектр → center_hz остаётся.
+    'if(msg.center_hz!=null)localCenter=(cur.transmitting&&cur.ctun&&!cur.dup)?cur.vfo_a_hz:msg.center_hz;' +
     'if(msg.span_hz!=null)localSpan=msg.span_hz||192000;' +
     '}' +
     'if(!isPending("freq")){vfoA=cur.vfo_a_hz||vfoA;}' +