debug: log raw DSM error response and API version; remove additional from list_dir

Diagnostic build to identify root cause of 408 on list_dir:
- client.py: log resolved version + NAS maxVersion before every request
- client.py: log full raw body on every error response
- tools/filestation.py: remove additional parameter entirely to test if
  any additional field triggers 408, or if the issue is elsewhere

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/mcp_synology_filestation/tools/filestation.py

@@ -151,7 +151,7 @@ def register_filestation(
                     "limit": limit,
                     "sort_by": sort_by,
                     "sort_direction": sort_direction,
-                    "additional": json.dumps(["size", "time"]),
+                    # DEBUG: no additional — testing if any additional causes 408
                 },
             )
         except SynologyError as e: