feat(docs): migrate developer docs to Zudoku

[Si40Code]

Summary

• migrate the CALL-E Developer Docs from the custom Vite/React renderer to Zudoku
• preserve and refine the existing Quickstart, authentication, calls, webhooks, errors, SDK, and changelog content
• publish clean prerendered guide routes, raw Markdown, llms.txt, llms-full.txt, sitemap, robots policy, and the raw OpenAPI contract
• add a read-only OpenAPI Reference, direct curl examples, and cross-links between Calls, errors, webhooks, and API Reference
• refresh the visual system with CALL-E styling, dark code blocks, roomier navigation, section anchors/TOC, a System/Light/Dark menu, and a desktop Scroll to Top control
• harden OSS deployment for clean URL aliases and exact public artifact verification

Why

The previous docs renderer returned empty content for raw Markdown paths and offered incomplete machine-readable discovery for AI agents and crawlers. Zudoku provides a maintained docs foundation while allowing the CALL-E visual layer and public API contract to remain explicit.

Developer impact

• human readers get searchable, anchorable, responsive documentation and API Reference pages
• AI agents and crawlers get non-empty Markdown routes, LLM discovery files, sitemap/robots metadata, and the raw OpenAPI YAML
• production deployment remains automatic after merge to main

API contract

Not changed.

Validation

• pnpm run validate
• TypeScript typecheck and Zudoku production build
• static artifact verification
• 11 OSS deployment unit tests
• 14 Playwright browser tests
• desktop and mobile visual QA in light, dark, and system modes
• deployed and reviewed at https://test-docs.heycall-e.com/calls