feat: adopt upstream agent versions

[chaliy]

Summary

• Refresh the local OpenAPI mirror from upstream everruns/everruns.
• Add agent version models and client methods across Rust, Python, and TypeScript.
• Mark new voice, payment, declarative capability, and debug summary endpoints as out of SDK scope pending API-surface decisions.

Test Plan

• Tests pass locally: just test
• Coverage ≥80%: existing suite maintained; targeted positive/negative tests added for agent version clients
• Linting passes: just lint, just pre-push
• Cookbook compile checks pass: just check-cookbook

Checklist

• Follows SDK API consistency guidelines
• Updated relevant specs (if applicable)
• Added/updated tests
• Updated documentation (if applicable)