feat: add recording toggle, stream stats UI

src/pygui/serialcomm/stream_reader.py

@@ -30,6 +30,8 @@ class StreamReader:
         self._thread: threading.Thread | None = None
         self._stop = threading.Event()
         self.error_count = 0
+        # Cumulative count of resync events (lost sync marker) for stream stats.
+        self.resync_count = 0
 
     def start(self) -> None:
         self._stop.clear()
@@ -158,6 +160,7 @@ class StreamReader:
             else:
                 # Resync: keep only trailing 0xAA if present, then read more.
                 resync_attempts += 1
+                self.resync_count += 1
                 if resync_attempts > _MAX_RESYNC_ATTEMPTS:
                     log.error(
                         "StreamReader: giving up after %d resync attempts "