Record Aura3D 2.0.4 publication receipts

[gchahal1982]

Summary

• mark Aura3D 2.0.4 as published after npm, GitHub, and production verification
• record immutable npm/GitHub/Vercel receipts
• replace stale release-candidate copy on the marketing page

Validation

• 29/29 npm packages use latest 2.0.4, match SHA-512 receipts, and are not deprecated
• pnpm --dir marketing build
• pnpm check:docs-site
• pnpm check:docs-codeblocks
• canonical homepage and Meshy pilot HTTP 200
• deployed Meshy GLB byte/hash/magic verification