fix: use alchemy rpc

[highskore]

No description provided.

[greg-rhinestone]

🤖 Automated review by Greg

PR Review

Summary: Adds an Alchemy RPC utility (src/utils/rpc.ts) with a chain-slug lookup table and falls back to viem's default public RPC when no API key or unsupported chain is encountered. Replaces bare http() calls across main.ts and tokens.ts with the new rpcTransport helper.

Risk: Low — purely improves RPC reliability; fallback preserves existing behaviour.

Suggestions:

• getRpcUrl returns an empty string '' for the fallback case and then rpcTransport calls http('') which technically works but is a bit odd. Returning null | string and branching on that (already done in rpcTransport) is cleaner — worth making the empty-string sentinel explicit in the comment.
• No chain slug entries for testnets (Sepolia, Base Sepolia, etc.). If this tool is used in dev/staging against testnets those calls will silently fall back to public RPCs. Fine for now, but worth a TODO comment.

Missing: Nothing critical.

Verdict: LGTM ✅