feat: publish Han Huan-Shou Dao showcase

[abyssalyanbin]

Summary

• add the Han Huan-Shou Dao demo, registry entry, reference plate, bilingual copy, and reference look-dev lighting
• sync the final procedural factory while keeping the showcase-only idle rock hook
• use responsive viewport fitting on mobile and retain the authored desktop hero camera

Verification

• npm run build
• desktop and 390x844 Playwright capture: full model fits the viewport
• composited canvas pixel audit: desktop and mobile nonblank
• runtime capture: 47 meshes, 87,490 triangles, 7 parts, 0 console errors

[hoainho]

Hi @abyssalyanbin the showcase looks awesome, you can help me fix for reference source with "contain" style instead of "cover"?

[abyssalyanbin]

Thanks — glad you like it. Switched the reference image to contain so it isn’t cropped; pushed to this PR.

[abyssalyanbin]

Synced with the latest main and resolved the registry conflict. The Han Huan-Shou Dao, Abyss Monster, and Boxing Man entries are all retained. Local build and showcase safety checks pass. Ready for another review.