CallOptions not exposed to Python

Currently, `SimplePublisher.publish()` and `SimpleNotifier.notify()` hardcode `CallOptions::for_publish(None, None, None)`. Users can't set TTL, priority, or message ID. Needs a Python CallOptions class.

Start at SimplePublisher.publish() and SimpleNotifier.notify(), then trace how Rust types are exposed through the Python bindings. Inspect the current CallOptions::for_publish(None, None, None) calls and the surrounding binding API. Done means Python callers can provide TTL, priority, and message ID through a CallOptions class used by both methods; run the existing test suite.

Written by the indexing model from the issue text.