refactor: pass Unitig objects directly instead of raw byte slices

Refactored `try_for_each_unitig` and related pipelines across `obidebruinj` and `obikpartitionner` to accept `Unitig` instances directly. This eliminates manual `Unitig::from_nucleotides()` conversions, simplifies the data flow, and reduces unnecessary allocation overhead.

src/obikpartitionner/src/index_layer.rs

@@ -107,8 +107,8 @@ impl KmerPartition {
         fs::create_dir_all(&layer_dir)?;
 
         let mut uw = Layer::<()>::unitig_writer(&layer_dir).map_err(olm_to_sk)?;
-        g.try_for_each_unitig(|nucs| {
-            uw.write(&obikseq::unitig::Unitig::from_nucleotides(nucs))
+        g.try_for_each_unitig(|unitig| {
+            uw.write(unitig)
         })?;
         uw.close()?;
 

src/obikpartitionner/src/merge_layer.rs

@@ -307,8 +307,8 @@ impl KmerPartition {
             g.compute_degrees_and_mark_starts();
             fs::create_dir_all(&new_layer_dir)?;
             let mut uw = Layer::<()>::unitig_writer(&new_layer_dir).map_err(olm_to_sk)?;
-            g.try_for_each_unitig(|nucs| {
-                uw.write(&obikseq::unitig::Unitig::from_nucleotides(nucs))
+            g.try_for_each_unitig(|unitig| {
+                uw.write(unitig)
             })?;
             uw.close()?;
             let n = g.len();

src/obikpartitionner/src/rebuild_layer.rs

@@ -168,8 +168,8 @@ impl KmerPartition {
         fs::create_dir_all(&dst_layer_dir)?;
 
         let mut uw = Layer::<()>::unitig_writer(&dst_layer_dir).map_err(olm_to_sk)?;
-        g.try_for_each_unitig(|nucs| {
-            uw.write(&obikseq::unitig::Unitig::from_nucleotides(nucs))
+        g.try_for_each_unitig(|unitig| {
+            uw.write(unitig)
         })?;
         uw.close()?;
         drop(g);