feat(gix): enumerate tree entries natively

Implement the managed full-tree NUL listing with native tree entries. Preserve Git's octal modes, object kinds, IDs and raw filename bytes for the existing tree parser. Other listing options continue through Git.

The staged version passes Ruff and Python syntax checks. Its SHA-1/SHA-256 native smoke and focused pytest selection pass: 26 passed in 3.86s.

Author: codex

git/_backend.py

@@ -144,8 +144,25 @@ def _rev_parse(repo: Any, args: List[str], kwargs: Dict[str, Any]) -> bytes:
     return str(_oid(repo, args[-1])).encode("ascii") + b"\n"
 
 
+def _ls_tree(repo: Any, args: List[str], kwargs: Dict[str, Any]) -> bytes:
+    if len(args) != 3 or args[:2] != ["-z", "--full-tree"]:
+        raise _Unsupported("tree options")
+    with repo.find_tree(_oid(repo, args[2])).iter() as entries:
+        return b"".join(
+            b"%06o %s %s\t%s\0"
+            % (
+                entry.mode(),
+                b"tree" if entry.kind() == "tree" else b"commit" if entry.kind() == "commit" else b"blob",
+                str(entry.id()).encode("ascii"),
+                entry.filename(),
+            )
+            for entry in entries
+        )
+
+
 _HANDLERS: Dict[str, Callable[[Any, List[str], Dict[str, Any]], bytes]] = {
     "rev_parse": _rev_parse,
+    "ls_tree": _ls_tree,
 }