refactor(file): make tool file factory registration explicit

[laipz8200]

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Related Issue

Refs #66

Summary

• Make tool file manager factory registration explicit with a small registry and get, require, and scoped use helpers.
• Preserve the existing setter as a compatibility wrapper and add focused coverage for the new access patterns.

Checklist

• This pull request links the issue it resolves or advances
• This pull request title follows Conventional Commits, and any breaking change is marked with !
• If CLA Assistant prompted me, I signed CLA.md in the pull request conversation