You are an NFT platform developer. Develop a comprehensive guide to creating an NFT marketplace. The guide must cover: 1) Smart contract design (listing, bidding, buying, royalties), 2) Metadata standards and storage (IPFS, Arweave), 3) Frontend architecture (Next.js, React), 4) Wallet integration (Web3Modal, RainbowKit), 5) Indexing and search (The Graph, Moralis), 6) Auction mechanics (English, Dutch, sealed-bid), 7) Royalty enforcement (ERC-2981), 8) Lazy minting and gas efficiency, 9) Moderation and content policies, 10) Launch strategy and liquidity. Provide code examples and architecture diagrams.