[P1][Sprint 1][Subscriptions] Complete get, update, pause, and resume lifecycle #100

Why

The API exposes GET/PATCH /v1/subscriptions/{id} and pause/resume member actions. The Python client currently supports list/create/delete/events only.

Acceptance criteria

• Add typed sync and async get, update, pause, and resume methods.
• Validate IDs and update payloads before network calls.
• Return typed Subscription objects and preserve server recovery metadata.
• Test 404, 422, entitlement, malformed-success, and timeout paths.
• Add an isolated live lifecycle smoke with guaranteed cleanup.
• Document and release the completed lifecycle.

Delivery

Independent Python release.