🔧 refactor(iter): simplify minimizer access via new canonical_minimizer_raw()

- Replace `canonicalMinimzer().map(|k| k.raw())` with direct call to new helper method
- Add `canonical_minimizer_raw()` in RollingStat for cleaner access of raw minimizer value

src/obiskbuilder/src/iter.rs

@@ -107,7 +107,7 @@ impl Iterator for SuperKmerIter<'_> {
                 continue;
             }
 
-            let min = self.stat.canonical_minimizer().map(|k| k.raw()).unwrap_or(0);
+            let min = self.stat.canonical_minimizer_raw().unwrap_or(0);
             let min_pos = self.stat.minimizer_position().unwrap_or(0);
 
             // ── 2. Minimizer change check ─────────────────────────────────────

src/obiskbuilder/src/rolling_stat.rs

@@ -266,6 +266,14 @@ impl RollingStat {
         }
     }
 
+    pub fn canonical_minimizer_raw(&self) -> Option<u64> {
+        if self.ready() {
+            self.minimier.front().map(|it| it.canonical)
+        } else {
+            None
+        }
+    }
+
     pub fn entropy(&self, order: usize) -> Option<f64> {
         if !self.ready() {
             return None;