ERC-1155 multi-token support (erc1155.zig)

[koko1123]

Motivation

ERC-20 and ERC-721 wrappers exist (erc20.zig, erc721.zig); ERC-1155 is the remaining mainstream token standard. Gaming/NFT integrators check for it on day one.

Scope

New src/erc1155.zig mirroring the erc721.zig pattern:

• Reads: balanceOf(account, id), balanceOfBatch, uri(id), isApprovedForAll
• Writes: setApprovalForAll, safeTransferFrom, safeBatchTransferFrom
• Event topics: TransferSingle, TransferBatch, ApprovalForAll, URI

Pointers

src/erc721.zig is the template (selector computation via keccak.zig, calls via contract.zig). Batch methods need dynamic-array ABI encoding — see abi_encode.zig tuple/array support. Add a refAllDeclsRecursive test (see src/mev_share.zig).