The file src/deepagents/middleware/filesystem.py contains duplicate/unused imports and a variable name that shadows the tool decorator.

Issues:

• TYPE_CHECKING, Runtime, and typing imports are duplicated or scattered
• Some imports can be moved under if TYPE_CHECKING to reduce runtime overhead
• Loop variable tool in _get_filesystem_tools shadows the imported tool decorator

Proposed cleanup:

• Consolidate imports at the top (PEP8-friendly)
• Move Runtime inside TYPE_CHECKING
• Rename loop variable to built_tool (avoid shadowing)

This is a small refactor-only change with no functional impact. I can open a PR if approved.