Instead of iterating all extracted Bytes features for every bytes-based rule,
build a prefix index keyed by fixed bucket sizes (4, 8, 16, 32, 64, 128, 256)
once per scope evaluation. Each bytes pattern is looked up in the largest
bucket that fits its length, then only candidates sharing that prefix are
compared, replacing the previous O(n) linear scan with an O(1) hash lookup.
Patterns shorter than the minimum bucket still fall back to the full scan.
Adds a test to verify correctness for exact match, startswith match, mismatch,
and short-bytes cases.
Closes: https://github.com/mandiant/capa/issues/2128
ed256d2416