actdown v0.1.1

Patch release of the development preview. The spec remains draft 0.1.

Fixed

• Reader conversion now starts at the first <main> element when present,
  excluding page headers and surrounding navigation. Empty link and button
  controls no longer produce semantic blocks. Pages without <main> retain
  full-document conversion.
• MCP serverInfo now reports the installed npm package version instead of
  a hardcoded release number.