fix: ESC now stops the active CW engine (Icom/Flex), not just WinKeyer

The ESC abort keyed WinkeyerStop unconditionally, so it never aborted the Icom
CI-V or Flex CWX keyer. Route the stop through cwSource like the panel Stop
button does.

frontend/src/App.tsx

@@ -2888,7 +2888,14 @@ export default function App() {
         const keyerLive = wkActiveRef.current;
         // ESC aborts the current CW transmission AND the auto-call loop, so it
         // won't resend after the gap — you must click a CQ macro to restart it.
-        if (keyerLive) { stopAutoCall(); WinkeyerStop().catch(() => {}); }
+        // Route the abort to whichever engine is active (was WinKeyer-only, so
+        // ESC didn't stop the Icom or Flex keyer).
+        if (keyerLive) {
+          stopAutoCall();
+          if (cwSourceRef.current === 'icom') IcomStopCW().catch(() => {});
+          else if (cwSourceRef.current === 'flex') FlexStopCW().catch(() => {});
+          else WinkeyerStop().catch(() => {});
+        }
         if (!keyerLive || wkEscClearsRef.current) {
           resetEntry();
           callsignRef.current?.focus();