feat: implement erc721 nft contract

[martinvibes]

Overview

Develop an ERC-721 smart contract for a "Verified Contributor" badge system. This badge will be awarded to contributors upon reaching specific milestones (such as writing guides or assisting others) and must be non-transferable (soulbound). The contract should leverage both the ERC721 and ERC721URIStorage standards for NFT and metadata management.

Requirements

ERC721 Implementation:
Create a contract inheriting from ERC721 and ERC721URIStorage.
Enable minting of badges to contributors who meet milestone criteria.
Soulbound Functionality:
Override all transfer and approval functions to prevent badge transfers, making the tokens soulbound.
Ensure badges cannot be transferred, sold, or delegated.
Badge Awarding Logic:
Implement internal logic or modifiers to check if a contributor qualifies for a badge.
Ensure only authorized accounts (e.g., contract owner or admin) can mint badges.
Metadata:
Store and retrieve badge metadata using the ERC721URIStorage standard.
Documentation:
Update project documentation with deployment, minting, and usage instructions.
Acceptance Criteria
The contract is deployed and integrates ERC721URIStorage.
Badges can be minted to contributors and are non-transferable.
All transfer and approval functions are disabled or reverted.
Metadata is accessible via tokenURI.
Documentation is updated with clear usage instructions.

[martinvibes]

closes #7

[Yunusabdul38]

LGTM