Add ChainGrid onchain game to Base ecosystem

[arawrdn]

Summary

This PR adds ChainGrid to the Base ecosystem.

Project name: ChainGrid
Description: A Base-native 9x9 strategy game where every move creates onchain patterns. Play, compete, and own your grid.
Repo: https://github.com/arawrdn/chaingrid
web: https://chaingrid-kohl.vercel.app/
Category: gaming
Subcategory: onchain game

ChainGrid showcases how games can leverage Base for onchain interactions and creativity. Players interact directly with Base smart contracts in every move, making each game session part of the network's permanent state.

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✅ JSON validated
✅ Logo added (/images/partners/chaingrid.png)
✅ Project built on Base mainnet

[vercel]

@arawrdn is attempting to deploy a commit to the Coinbase Team on Vercel.

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[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