Add Arborix bundle parsing and reconstruction

Implement portable Arborix container, section directory, nodes section, and
Merkle DAG reconstruction utilities in tricu libraries. Add byte/list helper
fixes needed for data-first recursion, validate node payloads, duplicate hashes,
and closed child references, and expose executable loading from a root hash.

Expand binary reader coverage with portable header/section tests, nodes-section
parsing, fixture bundle parsing, and execution checks for reconstructed
id/not?/map roots. Refresh fixture bundles and remove obsolete fixtures.

lib/bytes.tri

@@ -14,27 +14,29 @@ byteEq? = equal?
 bytesLength = length
 bytesAppend = append
 
-bytesTake_ = y (self n i remaining :
-  matchBool
+bytesTake_ = y (self remaining n i :
+  matchList
     t
-    (matchList
-      t
-      (h r : pair h (self n (succ i) r))
-      remaining)
-    (equal? i n))
+    (h r :
+      matchBool
+        t
+        (pair h (self r n (succ i)))
+        (equal? i n))
+    remaining)
 
-bytesTake = n bytes : bytesTake_ n 0 bytes
+bytesTake = n bytes : bytesTake_ bytes n 0
 
-bytesDrop_ = y (self n i remaining :
-  matchBool
-    remaining
-    (matchList
-      t
-      (_ r : self n (succ i) r)
-      remaining)
-    (equal? i n))
+bytesDrop_ = y (self remaining n i :
+  matchList
+    t
+    (_ r :
+      matchBool
+        remaining
+        (self r n (succ i))
+        (equal? i n))
+    remaining)
 
-bytesDrop = n bytes : bytesDrop_ n 0 bytes
+bytesDrop = n bytes : bytesDrop_ bytes n 0
 
 bytesSplitAt = n bytes : pair (bytesTake n bytes) (bytesDrop n bytes)