feat(ferry): generate Ferry Programs Python SDK

[haegwan]

Summary

• generate synchronous, asynchronous, and raw Ferry Programs clients
• add all request and response models for Meeting Updates and task mutations
• expose ferry_programs from the root client
• make SDK regeneration preserve the previous generated tree when Fern fails

Generated from the public API surface in sankaHQ/sanka-api#1386.

Verification

• uv sync frozen: passed
• Ruff: passed
• compileall over generated sources: passed
• synchronous and asynchronous Ferry Programs client smoke test: passed
• git diff check: passed

Release

No PyPI publish has been run.