fix: correct attestation vote percentage calculation (#297)

Use actual expected validator count from attestationCorrectness instead of
summing committee sizes, which was double-counting validators and causing
percentages to exceed 100%.

Author: samcm

src/pages/ethereum/slots/DetailPage.tsx

@@ -731,10 +731,7 @@ export function DetailPage(): JSX.Element {
                   attestationData={allAttestationVotes}
                   currentSlot={slot}
                   votedForBlocks={data.votedForBlocks}
-                  expectedValidatorCount={data.committees.reduce(
-                    (sum, committee) => sum + (committee.validators?.length ?? 0),
-                    0
-                  )}
+                  expectedValidatorCount={totalExpectedValidators}
                   isLoading={attestationVotesLoading}
                 />
                 <AttestationArrivalsChart