feat: add evolving-nft-automation tutorial

[jadonamite]

Summary

Adds a guide on building an Evolving NFT (ERC-721) using On-Chain SVG and a Node.js Automation Script.

Content

• Author: @jadonamite
• Stack: Solidity, Foundry, Viem.
• Key Features:
  • EvolvingNFT.sol: Stores stages and renders dynamic SVG via tokenURI.
  • keeper.ts: A polling script using viem to detect and trigger evolve().
  • Demonstration of metadata updates without IPFS.

Motivation

Teaches two core concepts: 1) How to make NFT metadata dynamic/on-chain, and 2) How to use external scripts ("Keepers") to automate blockchain interactions based on time.

Verification

• Verified Contract compiles and Base64 encodes correctly.
• Verified SVG renders in browser.
• Verified Keeper script successfully triggers state changes on Base Sepolia.

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1