feat: add Mash distance metric and rolling entropy support

Implement the Mash distance metric across the CLI, index, and compact vector traits. This includes adding a `Mash` variant to the `DistanceMetric` enum and `MetricArg` CLI argument, implementing the conversion from Jaccard distances using the standard mutation-rate estimator formula, and updating documentation with supported metrics and algorithmic references. Additionally, add an `entropy` method to rolling statistics for computing order-specific entropy.

src/obiskbuilder/src/rolling_stat.rs

@@ -196,13 +196,6 @@ impl RollingStat {
             .map(|raw| Minimizer::from_raw_unchecked(raw << (64 - self.m * 2)))
     }
 
-    pub fn entropy(&self, order: usize) -> Option<f64> {
-        if !self.ready() {
-            return None;
-        }
-        Some(self.entropy.entropy(order))
-    }
-
     pub fn normalized_entropy(&self) -> Option<f64> {
         if !self.ready() {
             return None;