Validate returned tool call arguments

[Kamilbenkirane]

Summary

• validate returned user-defined tool calls against their Pydantic parameter models
• normalize validated arguments with model_dump(mode="json", exclude_unset=True) while preserving provider extra fields
• enforce validation for non-streaming and final streaming text outputs

Validation

• pre-commit on commit/push: Ruff, Ruff format, mypy, test mypy, Bandit, coverage tests
• focused local run: uv run pytest tests/unit_tests/test_tool_call_validation.py tests/unit_tests/test_client.py tests/unit_tests/test_streaming.py
• focused local run: uv run ruff check src/celeste/tools.py src/celeste/client.py src/celeste/streaming.py tests/unit_tests/test_tool_call_validation.py
• focused local run: uv run mypy src/celeste/tools.py src/celeste/client.py src/celeste/streaming.py

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.