[fix](trx-server): clear CW history on ResetCwDecoder

ResetCwDecoder already bumped cw_decode_reset_seq but omitted the
history flush that APRS, FT8, and WSPR all perform.  Wire
clear_cw_history() into the handler to match the pattern.

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

src/trx-server/src/audio.rs

@@ -282,6 +282,10 @@ impl DecoderHistories {
         h.iter().map(|(_, evt)| evt.clone()).collect()
     }
 
+    pub fn clear_cw_history(&self) {
+        self.cw.lock().expect("cw history mutex poisoned").clear();
+    }
+
     // --- FT8 ---
 
     fn prune_ft8(history: &mut VecDeque<(Instant, Ft8Message)>) {

src/trx-server/src/rig_task.rs

@@ -437,6 +437,7 @@ async fn process_command(
             return snapshot_from(ctx.state);
         }
         RigCommand::ResetCwDecoder => {
+            ctx.histories.clear_cw_history();
             ctx.state.cw_decode_reset_seq += 1;
             let _ = ctx.state_tx.send(ctx.state.clone());
             return snapshot_from(ctx.state);