feat(sdk): validate Python contract facade

[swkeever]

Summary

• Add an idiomatic Python facade over a generated httpx boundary.
• Cover auth sessions, filtered database reads, byte-preserving storage, lock leases, and async realtime.
• Bind the shared SDK contract with Behave and add deterministic generation and package checks.

Verification

• 29 native tests passed with deprecations treated as errors.
• 5/5 live contract scenarios and 22/22 steps passed.
• Generation, Ruff, strict mypy, sdist, and wheel checks passed.
• The final coordinated gate passed on pinned commit 6007830.

Coordination

• VOL-930
• Coordination PR
• JavaScript PR
• Ruby PR

This private-repository pull request is a draft. No package was published.

[chatgpt-codex-connector]

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Reviewed commit: 60078306f3

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[swkeever]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. More of your lovely PRs please.

Reviewed commit: b11b044a27

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

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