Move volume file operations to unity_catalog module

[jacksandom]

Summary

• Relocates volume file operations from databricks_tools_core.file to databricks_tools_core.unity_catalog module
• Volume files are a Unity Catalog concept and belong with other UC operations (catalogs, schemas, tables, volumes)
• Updates MCP server imports to reference the new module location

Changes

• Moved: volume_files.py from file/ to unity_catalog/
• Updated: unity_catalog/__init__.py to export volume file functions
• Updated: file/__init__.py to remove volume file exports (now workspace-only)
• Updated: MCP server volume_files.py to import from unity_catalog instead of file

Affected Functions

The following functions are now available via databricks_tools_core.unity_catalog:

• list_volume_files
• upload_to_volume
• download_from_volume
• delete_volume_file
• delete_volume_directory
• create_volume_directory
• get_volume_file_metadata

[calreynolds]

Beautiful!