fix: replace blocking time.sleep with await asyncio.sleep in WhatsApp connect

time.sleep(1) inside async def connect() blocks the entire event
loop for 1 second. Replaced with await asyncio.sleep(1) to yield
control back to the event loop while waiting for the killed port
process to release.

gateway/platforms/whatsapp.py

@@ -181,8 +181,8 @@ class WhatsAppAdapter(BasePlatformAdapter):
             
             # Kill any orphaned bridge from a previous gateway run
             _kill_port_process(self._bridge_port)
-            import time
-            time.sleep(1)
+            import asyncio
+            await asyncio.sleep(1)
             
             # Start the bridge process in its own process group.
             # Route output to a log file so QR codes, errors, and reconnection