Add generated Developer Cloud clients to the Python SDK

[sanka-change-bot]

Summary

Generate 18 V2 Cloud Run, receipt, certificate and Fleet operations from the shared SDK contract, with synchronous and asynchronous clients. Preserve existing error types and free local migration. Add transport tests and scoped usage docs; prepare 0.2.7 without publishing.

Audit

• Requester: @haegwan
• Authoring identity: Sanka Change Bot
• Head SHA: 9a031117cc972c40760fe6da25ad5d34e260d854
• Risk: medium
• Deploy mode: none
• Production surface: Python SDK package

Validation

• 32 unittest cases passed; one existing opt-in real CLI test skipped. Binary, cap, workspace, idempotency and async availability checks passed. -> reported passed
• uv build produced the 0.2.7 wheel and sdist. -> reported passed
• No-local-check reason: Final unittest and package build completed successfully on this exact source before PR submission; reuse their recorded results without duplicate validation.
• Required GitHub checks must complete before landing.
• Valid review findings must be addressed before landing.

Change Safety

• Data or migration impact: No database change or package publication.
• Rollback: Revert the generated SDK surface; preserve installed versions and API receipts.
• Monitoring: Repository deployment helper smoke checks.

Approval And Deployment Authorization

• The PR is ready for final human review; no intended code changes remain.
• The listed head SHA is the exact revision being presented for approval.

By approving this PR, the reviewer authorizes merge of the exact approved revision. This repository has no production deployment in this flow. A later push requires a new approval.