docs: add changelog entry for #4485

Author: barlowa124

changes/4485.bugfix.md

@@ -0,0 +1,5 @@
+Reject invalid consolidated metadata listings at parse time. Listing keys
+with empty or reserved path segments (``.``, ``..``, ``zarr.json``,
+``__``-prefixed) now raise ``MetadataValidationError``, as do listings
+whose parent group entry is missing or that place a node below an array;
+both previously surfaced as ``KeyError`` or left the group unopenable.