* Add MongoDB-backed NotesTool with CRUD actions and unit tests
* NotesTool: enforce single note per user, require decoded_token['sub'] user_id, fix tests
* chore: remove accidentally committed results.txt and ignore it
* fix: remove results.txt, enforce single note per user, add tests
* refactor: update NotesTool actions and tests for clarity and consistency
* refactor: update NotesTool docstring for clarity
* refactor: simplify MCPTool docstring and remove redundant import in test_notes_tool
* lint: fix test
* refactor: remove unused import from test_notes_tool.py
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Co-authored-by: Alex <a@tushynski.me>
