feat(docs): publish Goal API documentation

[Si40Code]

Summary

• sync the canonical CALL-E Developer API OpenAPI 0.6 contract from s-eleven-mono
• publish the Goal Runs guide, navigation, API Reference routes, error guidance, and discovery artifacts
• align the docs palette and Goal Runs sidebar with CALL-E Web
• document finalized unsigned terminal webhooks and safe event handling
• clarify the current Python and TypeScript SDK release boundary

Release impact

Merging publishes the Goal Runs documentation to docs.heycall-e.com through the protected production OSS workflow. Existing Calls behavior remains compatible.

Validation

• pnpm run validate (25.43s)
• TypeScript typecheck and Zudoku production build
• static dist, sitemap, LLM discovery, and OpenAPI verification
• 11 OSS deployment tests
• 16 Playwright tests
• canonical, docs, and public OpenAPI SHA-256: 6c8200cb327d8c125eeed9eb55eeacfbe53cb5dc9044589bb07d07614189786b

Deployment

After CI passes, this PR is intended to be merged for the Goal documentation release. The merge-triggered Deploy docs to OSS workflow remains the only production deployment path.