Complete the renderer TypeScript migration and remove allowJs #26

Outcome

Every maintained Markover source file is strictly typed and the temporary JavaScript migration boundary is removed before focused preview.

Stack position

7 of 7 — top of the TypeScript migration stack.

Acceptance criteria

• The renderer, documentation-site script, and every remaining maintained test are converted.
• The existing framework-free UI and all user-visible behavior remain unchanged.
• GitHub Pages deployment consumes generated output rather than committed generated JavaScript.
• allowJs and all migration-only exceptions are removed.
• ESLint and TypeScript enforce the final strict policy over all maintained source.
• Vendor/generated JavaScript is the only JavaScript left outside unavoidable configuration.
• Local checks, packaging checks, and both supported Node CI jobs pass.

Intended PR sub-stack

Bottom to top:

1. Convert the renderer, YAML entry point, and renderer-dependent tests to strict TypeScript while temporarily retaining the documentation-site JavaScript boundary.
2. Convert the documentation site and remaining tests, deploy generated Pages output through GitHub Actions, remove allowJs and every migration exception, and close this issue.

Both PRs preserve the framework-free runtime architecture and user-visible behavior. Renderer refactoring requires concrete evidence and remains an input to #36 rather than speculative scope in this migration.