Add AI zine generator section to rPubs landing page with style showcase
and links to /rpubs/zine and zine.mycofi.earth. Add /zine sub-route that
redirects to canvas with ?tool=folk-zine-gen. Add ?tool= URL param
support to canvas for auto-spawning any registered shape on load.
Also adds folk-image and folk-bookmark shape components.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
