Switch to parallel network requests

[ECWireless]

Close this issue if all data is able to be moved to a subgraph

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Location: pages/api/pending-stake/[address].tsx, pages/api/score/[address].tsx, pages/api/regions/index.ts

Problem: Multiple API calls are made sequentially when they could run in parallel.

Example Fix:

// Before (sequential - 5s total)
const currentRound = await readContract(...);
const pendingStake = await readContract(...);
const pendingFees = await readContract(...);

// After (parallel - 2s total)
const currentRound = await readContract(...);
const [pendingStake, pendingFees] = await Promise.all([
  readContract(...),
  readContract(...)
]);

We could also probably just make a single RPC ping with viem's readContracts method, which would make uncached page loads multiple times faster.