🧹 Remove unused defaultdict import and clean up dead code in scout.py

[wjohns989]

🎯 What: Removed the unused defaultdict import, as well as several other unused imports (asyncio, MemoryRecord, Dict, Any, Tuple), in muninn/retrieval/scout.py. I also removed the unused local variables record_map and records, along with the metadata fetch call that populated them.
💡 Why: This improves maintainability and readability by cleaning up the import block and eliminating dead code. It also slightly optimizes performance by avoiding an unnecessary get_by_ids metadata fetch during the search reranking step.
✅ Verification: Verified via uv run ruff check that all unused imports and variables were successfully removed. I also executed the full test suite using uv run pytest, which passed successfully, confirming no functionality was broken.
✨ Result: A cleaner, more maintainable scout.py file with no unused imports and a tiny performance improvement.

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PR created automatically by Jules for task 4838458965883341088 started by @wjohns989

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[gemini-code-assist]

Code Review

This pull request refactors muninn/retrieval/scout.py by removing unused imports and a redundant code block that fetched metadata records. Additionally, it improves code hygiene by cleaning up trailing whitespace and ensuring a proper newline at the end of the file. I have no feedback to provide as there were no review comments to evaluate.