Show token cost breakdown in check output

[gauravxthakur]

Description

Add a summary table to evalview check output showing token usage breakdown: input tokens, output tokens, cached tokens, and estimated cost.

Related Issue

Fixes #146

Type of Change

• New feature (non-breaking change which adds functionality)

Changes Made

What I added:

• Token summary table: Shows input/output/cached tokens and total cost
• Baseline comparison: Shows if you're using more/less tokens than before
• JSON output: Includes the same data when you use --json flag
• Graceful handling: Won't crash if token data isn't available

Testing

Test Configuration

• Python Version: 3.13.7
• OS: Windows

Tests Added/Modified

• Unit tests added/updated
• All tests pass locally
• Test coverage maintained or improved

Manual Testing Steps

Run unit tests to verify token summary functionality: py -m pytest tests/test_check_cmd.py::test_check_json_includes_token_usage_and_cost_summary tests/test_check_cmd.py::test_check_json_omits_token_usage_when_unavailable -v

Checklist

Code Quality

• My code follows the project's style guidelines
• I have performed a self-review of my own code

Documentation

• I have added docstrings to new functions/classes

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Dependencies

• I have checked that no new dependencies were added unnecessarily

Breaking Changes

None.

Additional Notes

There's a type checking error in the CI/CD pipeline. The functionality works correctly (all tests pass locally), but there's a type annotation issue that needs to be resolved. I would really appreciate some help in identifying and fixing this error.

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By submitting this pull request, I confirm that:

• I have read and followed the CONTRIBUTING.md guidelines
• I agree to the project's CODE_OF_CONDUCT.md
• My contribution is my own work and I have the right to contribute it