feat: update Gumroad URL to live product

feat: Get Pro button + Pro README section

fix: correct BuyMeACoffee link to artel3d

seo: optimize meta tags and README for search visibility

fix: restore SEO meta tags and BuyMeACoffee button

fix: restore pre-built deploy + EXR texture mapping fix

fix: use app_build_command to let HF build the app

fix: EXR black screen + restore proper deployment from canva3d-hf

fix: rebuild from index.tsx entry — ImportPanel fully removed from bundle

fix: remove importmap conflict, clean HTML template

fix: deploy standalone Viewer3D without ImportPanel backend dependency

deploy: push compiled Canva3D app to replace default template

feat: add SEO meta tags and Open Graph to index.html

feat: wire split panel — ImportPanel + Viewer3D assembled