fix: Use search_params.limit value instead of constant

[whiterabbit1983]

[!IMPORTANT] Replaced constant k with search_params.limit for dynamic document processing in search functions and updated models.

• Behavior:
  • Replace constant k with search_params.limit in search_user_docs() and search_agent_docs() for maximal_marginal_relevance() call.
  • Allows dynamic control over document processing based on search_params.limit.
• Functions:
  • Affects search_user_docs() and search_agent_docs() in search_docs.py.
• Models:
  • Change snippets to snippet in DocReference in Docs.py and models.tsp.
• Misc:
  • Add RootModel import in Tools.py.

^{This description was created by for 4c47490d2b380d6d5fa1e01fca65bb6f88f8ae76. It will automatically update as commits are pushed.}

[sweep-ai[bot]]

Hey @whiterabbit1983, here are examples of how you can ask me to improve this pull request:

@sweep Fix the CI errors.

@sweep Add unit tests for `search_user_docs` and `search_agent_docs` functions that verify the maximal marginal relevance (MMR) functionality works correctly with the new dynamic `search_params.limit` value instead of the hardcoded `k=3`. Tests should cover:
- Different limit values (e.g., 1, 5, 10)
- Cases where MMR is enabled vs disabled via `mmr_strength`
- Verify the returned document count matches the requested limit

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