feat: add faith assignment submission for upgradeable contracts

[rayeberechi]

Summary

This PR implements my submission for the Upgradeable Contracts assignment. Specifically, it adds:

• My submission markdown file (sessions/upgradable contracts/assignments/faith.md).
• A link to my upgradeable smart contracts monorepo, which contains 6 individual Foundry projects converted to the OpenZeppelin Proxy pattern (Auction, Crowdfunding, Escrow Factory, MilestoneJob Factory, TimeLock, and Todo), alongside my Diamond Standard implementation.
• A link to my technical article on the Diamond Standard published on HackMD.

Testing

• Unit tests added
• Tests passing locally

Notes

• Architecture: Structured the OpenZeppelin suite as a monorepo where each upgraded contract is isolated in its own complete Foundry environment (with dedicated src, test, and lib folders) to ensure modularity.
• Testing: Achieved a 100% passing rate locally using Foundry (forge test). Tests specifically validate the deployment of the implementation logic, the ERC1967Proxy routing, and proper state initialization using abi.encodeWithSelector.
• Trade-offs/Assumptions: Leveraged OpenZeppelin's heavily audited Initializable extension and proxy contracts rather than writing custom delegatecall assembly. This prioritizes industry-standard security and maintainability over raw gas micro-optimizations.