pub const fn pack(layer: Layer, freq_score: u64) -> u64Expand description
Pack (layer, freq_score) into a single u64 index value. freq_score is
saturated to MAX_FREQ_SCORE if it exceeds the field, never wrapped:
for an order-by-value structure a wraparound would invert priority (a very
high freq would pack to a tiny value and rank last), whereas clamping keeps
“higher freq → higher-or-equal priority”. Real freqs (≤ ~50k) are far
inside the field, so this only matters as a defensive guarantee.