refactor(question-classifier)!: bundle runtime dependencies

[laipz8200]

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Related Issue

Refs #66

Summary

Bundle the question classifier node runtime collaborators behind a dedicated dependency object while keeping the legacy constructor keywords available for compatibility. Export the new dependency type and extend the node tests to cover bundled and legacy initialization paths.

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