feat(rep): source total supply from the live REP contract

[jubalm]

Summary

The /rep page added by #167 hardcodes the REP total supply and leaves an inline TODO(publish) to manually re-read totalSupply() before publishing. The current values can become stale as the token supply changes, and the three related fields can drift apart:

• totalSupply
• totalSupplyRaw
• totalSupplyReadOn

Goal

Source the displayed REP total supply from the current Ethereum mainnet contract at build/publish time, or through another agreed data pipeline, so maintaining the page does not depend on remembering a manual TODO.

Acceptance criteria

• Read totalSupply() from 0xCf6A0A7826fa124B7705d6f3c675eAD76f1e540D on Ethereum mainnet (chain ID 1).
• Derive the formatted supply and exact raw value from the same on-chain response, respecting the contract's 18 decimals.
• Derive totalSupplyReadOn from that same read; the three values cannot be updated independently.
• Document the RPC/provider configuration and define failure behavior so a failed read does not silently publish stale data.
• Keep the public /rep page static and free of a client-side RPC dependency unless the architecture intentionally changes.
• Add appropriate validation or test coverage and verify with the normal typecheck, lint, and build commands.

Reference

• PR feat(rep): add REP token contract reference page #167
• src/pages/rep.astro TODO