[fix](trx-frontend-http): guard scheduleSpectrumDraw from TDZ during init

scheduleSpectrumDraw references a let-bound variable that hasn't been
initialized yet when setTheme runs at startup. Wrap in try/catch so the
early call is silently skipped.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js

@@ -632,7 +632,7 @@ function setTheme(theme) {
   }
   // Invalidate cached bookmark chip colours so they pick up the new theme palette.
   if (typeof bmRevision !== "undefined") bmRevision++;
-  if (typeof scheduleSpectrumDraw === "function") scheduleSpectrumDraw();
+  try { if (typeof scheduleSpectrumDraw === "function") scheduleSpectrumDraw(); } catch (_) {}
 }
 
 // ── Style / palette system ────────────────────────────────────────────────────