fix(python): bound galaxy-browse --depth; assert no _text leak in JSON

Guard _galaxy_browse against unbounded recursion by rejecting --depth
values outside [0, 50] with a descriptive BadParameter. Add test coverage
for --depth 99 and --depth -1 rejection, and assert _text is never
present in the JSON output from galaxy-browse.

clients/python/src/zb_mom_ww_mxgateway_cli/commands.py

@@ -1086,8 +1086,8 @@ async def _galaxy_discover(**kwargs: Any) -> dict[str, Any]:
 
 async def _galaxy_browse(**kwargs: Any) -> dict[str, Any]:
     depth = int(kwargs["depth"])
-    if depth < 0:
-        raise click.BadParameter("must be non-negative", param_hint="--depth")
+    if depth < 0 or depth > 50:
+        raise click.BadParameter("--depth must be between 0 and 50", param_hint="--depth")
     options = BrowseChildrenOptions(
         category_ids=tuple(kwargs.get("category_ids") or ()),
         template_chain_contains=tuple(kwargs.get("template_chain_contains") or ()),