Fix Python cookbook recipes to use correct async SDK API

All 5 Python recipes and their markdown docs used a synchronous,
kwargs-based API that doesn't match the real github-copilot-sdk:

- client.start() -> await client.start() (all methods are async)
- create_session(model=...) -> create_session(SessionConfig(model=...))
- session.send(prompt=...) -> session.send(MessageOptions(prompt=...))
- session.wait_for_idle() -> session.send_and_wait() (wait_for_idle doesn't exist)
- event['type']/event['data']['content'] -> event.type/event.data.content
- All code wrapped in async def main() + asyncio.run(main())

Verified all imports resolve against github-copilot-sdk.

cookbook/copilot-sdk/python/recipe/persisting_sessions.py

@@ -1,36 +1,41 @@
 #!/usr/bin/env python3
 
-from copilot import CopilotClient
+import asyncio
+from copilot import CopilotClient, SessionConfig, MessageOptions
 
-client = CopilotClient()
-client.start()
+async def main():
+    client = CopilotClient()
+    await client.start()
 
-# Create session with a memorable ID
-session = client.create_session(
-    session_id="user-123-conversation",
-    model="gpt-5",
-)
+    # Create session with a memorable ID
+    session = await client.create_session(SessionConfig(
+        session_id="user-123-conversation",
+        model="gpt-5",
+    ))
 
-session.send(prompt="Let's discuss TypeScript generics")
-print(f"Session created: {session.session_id}")
+    await session.send_and_wait(MessageOptions(prompt="Let's discuss TypeScript generics"))
+    print(f"Session created: {session.session_id}")
 
-# Destroy session but keep data on disk
-session.destroy()
-print("Session destroyed (state persisted)")
+    # Destroy session but keep data on disk
+    await session.destroy()
+    print("Session destroyed (state persisted)")
 
-# Resume the previous session
-resumed = client.resume_session("user-123-conversation")
-print(f"Resumed: {resumed.session_id}")
+    # Resume the previous session
+    resumed = await client.resume_session("user-123-conversation")
+    print(f"Resumed: {resumed.session_id}")
 
-resumed.send(prompt="What were we discussing?")
+    await resumed.send_and_wait(MessageOptions(prompt="What were we discussing?"))
 
-# List sessions
-sessions = client.list_sessions()
-print("Sessions:", [s["sessionId"] for s in sessions])
+    # List sessions
+    sessions = await client.list_sessions()
+    print("Sessions:", [s.session_id for s in sessions])
 
-# Delete session permanently
-client.delete_session("user-123-conversation")
-print("Session deleted")
+    # Delete session permanently
+    await client.delete_session("user-123-conversation")
+    print("Session deleted")
 
-resumed.destroy()
-client.stop()
+    await resumed.destroy()
+    await client.stop()
+
+if __name__ == "__main__":
+    asyncio.run(main())