Feat/nft ecosystem

[divisio74]

NFT Ecosystem for Gno.land

This PR introduces a complete NFT ecosystem consisting of two interconnected realms that work together to enable NFT discovery, verification, and trading on Gno.land.

Overview

This submission includes two realms:

1. NFT Registry (r/pierre115/nftregistry) - A decentralized registry for discovering and verifying GRC-721 collections
2. NFT Marketplace (r/pierre115/gnopensea) - A complete marketplace for trading NFTs with automatic royalty distribution

These realms are designed to work together: the registry provides collection discovery and verification, while the marketplace handles the actual trading with full GRC-721 and GRC-2981 support.

Why Both Realms in One PR?

The marketplace depends on the registry for collection discovery and verification. By submitting them together:

• ✅ CI checks pass (no missing dependencies)
• ✅ Reviewers can see the complete ecosystem
• ✅ Both realms can be merged atomically, ensuring consistency
• ✅ The integration between both realms can be validated

NFT Registry (r/pierre115/nftregistry)

A central registry where NFT collections can register themselves and get verified by administrators.

Features:

• Self-registration system (collections register themselves)
• Admin verification workflow for legitimate collections
• Query functions (by address, all collections, verified only)
• Admin management (owner can add/remove admins)
• Web interface with statistics and collection listings

Use case: Marketplaces and users can discover trusted NFT collections through this registry.

NFT Marketplace (r/pierre115/gnopensea)

A complete marketplace for buying and selling GRC-721 NFTs with automatic payment distribution.

Features:

• Create, update, and cancel listings
• Buy NFTs with automatic payment distribution:
  • Seller receives sale price minus fees and royalties
  • Creator receives royalties (GRC-2981)
  • Marketplace collects configurable fees (0-10%, default 2.5%)
• Admin moderation system
• Complete sale history and statistics
• Web interface with price breakdowns and transaction history

Use case: NFT owners can list their tokens for sale, and buyers can purchase them with transparent pricing and automatic royalty payments.

Integration Between Realms

The marketplace uses the registry to:

• Verify collections are legitimate before allowing listings
• Display collection metadata (name, symbol, verification status)
• Provide users with trusted collection information

Example flow:

1. NFT collection deploys and registers with nftregistry
2. Admin verifies the collection in the registry
3. NFT owner lists their token on gnopensea
4. Buyer purchases the NFT with automatic royalty distribution
5. Sale is recorded with full transparency

Standards Compliance

Both realms fully implement Gno.land standards:

• GRC-721: Complete NFT standard with transfer, approval, and metadata
• GRC-2981: Royalty standard for automatic creator compensation