feat(gix): enumerate reference names natively

List native reference names in Git's order for the managed `for-each-ref` format and literal prefixes. Keep glob patterns, pseudo refs and other formats on the CLI rather than interpreting them as plain prefixes.

The staged version passes Ruff and Python syntax checks. Its SHA-1/SHA-256 native smoke and focused pytest selection pass: 6 passed in 1.88s.

Author: codex

git/_backend.py

@@ -176,10 +176,29 @@ def _symbolic_ref(repo: Any, args: List[str], kwargs: Dict[str, Any]) -> bytes:
     return target + b"\n"
 
 
+def _for_each_ref(repo: Any, args: List[str], kwargs: Dict[str, Any]) -> bytes:
+    if not args or args[0] != "--format=%(refname)":
+        raise _Unsupported("reference format/options")
+    split = args.index("--") if "--" in args else len(args)
+    if args[1:split] or len(args[split + 1 :]) > 1:
+        raise _Unsupported("root refs or reference options")
+    prefix = os.fsencode(args[-1]) if len(args) > split + 1 else b""
+    if any(char in prefix for char in b"*?["):
+        raise _Unsupported("reference glob patterns")
+    with repo.references().all() as refs:
+        names = [ref.name() for ref in refs]
+    return b"".join(
+        name + b"\n"
+        for name in sorted(names)
+        if not prefix or name == prefix or name.startswith(prefix.rstrip(b"/") + b"/")
+    )
+
+
 _HANDLERS: Dict[str, Callable[[Any, List[str], Dict[str, Any]], bytes]] = {
     "rev_parse": _rev_parse,
     "ls_tree": _ls_tree,
     "symbolic_ref": _symbolic_ref,
+    "for_each_ref": _for_each_ref,
 }