⚡ Optimize simple-auth-client by making wait_for_callback async

What: Modified CallbackServer.wait_for_callback in mcp_simple_auth_client/main.py to be an async function, utilizing await asyncio.sleep(0.1) instead of the blocking time.sleep(0.1). The call in callback_handler was also updated to await this execution.
Why: The previous implementation used the blocking time.sleep, which stalled the asyncio event loop and delayed other background coroutines running concurrently, making the application unresponsive during the waiting period.
Measured Improvement:
Baseline: Max event loop delay was measured at ~0.910s when simulating a 1s wait.
After fix: Event loop remained fully responsive (Max delay 0.000s) during the wait period.

Author: saquibsaifee

examples/clients/simple-auth-client/mcp_simple_auth_client/main.py

@@ -146,15 +146,15 @@ def stop(self):
         if self.thread:
             self.thread.join(timeout=1)
 
-    def wait_for_callback(self, timeout: int = 300):
+    async def wait_for_callback(self, timeout: int = 300):
         """Wait for OAuth callback with timeout."""
         start_time = time.time()
         while time.time() - start_time < timeout:
             if self.callback_data["authorization_code"]:
                 return self.callback_data["authorization_code"]
             elif self.callback_data["error"]:
                 raise Exception(f"OAuth error: {self.callback_data['error']}")
-            time.sleep(0.1)
+            await asyncio.sleep(0.1)
         raise Exception("Timeout waiting for OAuth callback")
 
     @property
@@ -194,7 +194,7 @@ async def callback_handler() -> AuthorizationCodeResult:
                 """Wait for OAuth callback and return auth code, state, and iss."""
                 print("⏳ Waiting for authorization callback...")
                 try:
-                    auth_code = callback_server.wait_for_callback(timeout=300)
+                    auth_code = await callback_server.wait_for_callback(timeout=300)
                     return AuthorizationCodeResult(code=auth_code, state=callback_server.state, iss=callback_server.iss)
                 finally:
                     callback_server.stop()