feat(udp): Highlight Callsign and Replay — the decoder becomes log-aware

Message 13 paints callsigns in WSJT-X/JTDX's own Band Activity window with
verdicts from the same cluster status cache that colours the spot grid:
watchlist pink, new DXCC green, new band for its entity orange. Deduplicated
per instance+call+verdict, one datagram each; a verdict that lapses (the
operator worked them) clears that call, and turning the option off clears
everything via the protocol's CLEARALL!. Off by default, switch in the
Connections panel.

Message 7 asks a program heard for the first time this session to replay the
decodes already on its screen, so the FT decodes panel starts full instead of
empty until the next period. Replayed lines arrive marked not-new and are
shown but never auto-answered — the auto-caller now checks, on top of its
30-second freshness gate.

frontend/src/App.tsx

@@ -2566,6 +2566,10 @@ export default function App() {
     for (const d of decodes) {
       const seenKey = `${d.call}|${d.ms ?? d.at}|${d.instance ?? ''}`;
       if (autoSeenRef.current.has(seenKey)) continue;
+      // A Replay's resent history is display-only: answering a line the far
+      // end already dropped would fail anyway, and doing it at startup — the
+      // moment replays arrive — would be a transmitter firing on old news.
+      if ((d as any).is_new === false) { autoSeenRef.current.add(seenKey); continue; }
       // Only decodes from the CURRENT period are worth answering: replying to a
       // slot that has closed asks the far end to match a decode it has dropped.
       if (now - Date.parse(d.at) > 30_000) { autoSeenRef.current.add(seenKey); continue; }