bug: FeeHistory block number overflow — uint64 cast to int64 without range check

[Aboudjem]

Bug Description

In rpc/backend/chain_info.go, FeeHistory casts block numbers to int64 without range checks:

blockNumber := int64(blkNumber) //#nosec G115
blockEnd := int64(lastBlock)    //#nosec G115

When blkNumber exceeds math.MaxInt64, the cast wraps to a negative value.

Impact

Block numbers > MaxInt64 produce incorrect negative values, potentially returning wrong fee history data.

Proposed Fix

Add range check before the cast: return error if value exceeds int64 range.

[linear]

EVM-443

[swift1337]

Closing for being a low-effort AI submission.