Expose remaining Topic and TopicDetails fields in the Python SDK

[mattp5657]

Title

Expose remaining Topic and TopicDetails fields in the Python SDK

Description

The Python SDK's Topic and TopicDetails classes expose only a subset of the
fields available on their Rust counterparts (iggy::prelude::Topic /
TopicDetails), so a topic's full configuration can't be read from Python and
those fields can't be asserted in tests.

Already exposed:

• TopicDetails: id, name, messages_count, partitions_count,
  compression_algorithm, replication_factor
• Topic: id, name, messages_count, partitions_count

This issue tracks adding getters (with docstrings) for the remaining fields.

TopicDetails:

• created_at (IggyTimestamp)
• size (IggyByteSize)
• message_expiry (IggyExpiry)
• max_topic_size (MaxTopicSize)
• partitions (Vec<Partition>)

Topic:

• created_at (IggyTimestamp)
• size (IggyByteSize)
• message_expiry (IggyExpiry)
• compression_algorithm (CompressionAlgorithm)
• max_topic_size (MaxTopicSize)
• replication_factor (u8)

Affected area / component

Python SDK (foreign/python)

Proposed solution

Add #[getter] methods to Topic and TopicDetails in
foreign/python/src/topic.rs, regenerate apache_iggy.pyi via stub_gen, and
add corresponding tests. For the tri-state enum fields, settle on a faithful
Python representation (e.g. small wrapper classes) before implementing.

Alternatives considered

No response

Contribution

I will work on this once 3572 is closed.