[fix](trx-frontend): use server decode history only

Remove APRS client-side persistence, reset decode views before replay,
and clear decode panes only after the server clears its history.

Co-authored-by: OpenAI Codex <codex@openai.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/plugins/cw.js

@@ -48,9 +48,18 @@ if (cwToneInput) {
   });
 }
 
-document.getElementById("cw-clear-btn").addEventListener("click", async () => {
+window.resetCwHistoryView = function() {
   cwOutputEl.innerHTML = "";
-  try { await postPath("/clear_cw_decode"); } catch (e) { console.error("CW clear failed", e); }
+  cwLastAppendTime = 0;
+};
+
+document.getElementById("cw-clear-btn").addEventListener("click", async () => {
+  try {
+    await postPath("/clear_cw_decode");
+    window.resetCwHistoryView();
+  } catch (e) {
+    console.error("CW clear failed", e);
+  }
 });
 
 // --- Server-side CW decode handler ---