refactor: implement RoutableSuperKmer and update k-mer indexing pipeline

Replace raw SuperkMer routing with a new RoutableSuperKimer type that embeds canonical sequences and precomputed minimizers, enabling direct partition routing via hash. Update the build pipeline to yield RoutableSuperKmers throughout (builder, scatterer), refactor FASTA/unitig export commands to use the new type and compressed outputs (.fasta.gz, .unitigs.fasta.zst), revise SuperKmer header to store n_kmers instead of seql (avoiding 256-byte wrap), and update documentation to reflect minimizer-based theory, two evidence-encoding strategies for unitig-MPHF indexing (global offset vs. ID+rank), and the new obipipeline library architecture with parallel workers, biased scheduling, and error handling.

doc/implementation/pipeline/index.html

@@ -12,7 +12,7 @@
         <link rel="prev" href="../chunkreader/">
       
       
-        <link rel="next" href="../storage/">
+        <link rel="next" href="../obipipeline/">
       
       
         
@@ -230,7 +230,7 @@
   
   
     <li class="md-nav__item">
-      <a href="../../theory/kmers/" class="md-nav__link">
+      <a href="../../kmers/" class="md-nav__link">
         
   
   
@@ -313,6 +313,34 @@
   
   
   
+    <li class="md-nav__item">
+      <a href="../../theory/minimizer/" class="md-nav__link">
+        
+  
+  
+  <span class="md-ellipsis">
+    
+  
+    Minimizer selection
+  
+
+    
+  </span>
+  
+  
+
+      </a>
+    </li>
+  
+
+              
+            
+              
+                
+  
+  
+  
+  
     <li class="md-nav__item">
       <a href="../../theory/indexing/" class="md-nav__link">
         
@@ -633,6 +661,34 @@
   
   
   
+    <li class="md-nav__item">
+      <a href="../obipipeline/" class="md-nav__link">
+        
+  
+  
+  <span class="md-ellipsis">
+    
+  
+    obipipeline library
+  
+
+    
+  </span>
+  
+  
+
+      </a>
+    </li>
+  
+
+              
+            
+              
+                
+  
+  
+  
+  
     <li class="md-nav__item">
       <a href="../storage/" class="md-nav__link">
         
@@ -683,6 +739,34 @@
 
               
             
+              
+                
+  
+  
+  
+  
+    <li class="md-nav__item">
+      <a href="../unitig_evidence/" class="md-nav__link">
+        
+  
+  
+  <span class="md-ellipsis">
+    
+  
+    Unitig evidence encoding
+  
+
+    
+  </span>
+  
+  
+
+      </a>
+    </li>
+  
+
+              
+            
           </ul>
         </nav>