Add JSON output format for CI/CD pipeline integration

[UrRhb]

Description

burn0 currently outputs cost data in a human-readable format to the terminal. It would be great to have a --json flag for npx burn0 report that outputs structured JSON, making it easy to integrate with CI/CD pipelines, dashboards, or custom tooling.

Expected behavior

npx burn0 report --json

Should output something like:

{
  "total": 4.32,
  "calls": 47,
  "services": {
    "openai": { "cost": 3.80, "calls": 35 },
    "anthropic": { "cost": 0.52, "calls": 12 }
  },
  "period": "today"
}

Implementation hints

• The report command likely lives in src/ — find the current report formatter
• • Add a --json CLI flag that switches the output formatter
• • • Reuse existing cost aggregation logic, just serialize as JSON instead of formatted text
• • • • Add a test that verifies JSON output is valid and contains expected fields

This is a good first issue because

• Clear input/output specification
• • Doesn't require understanding the core cost-tracking internals
• • • Great way to learn the CLI architecture

[MANASAB805]

Hello, I’m interested in taking up this issue. It aligns well with my skills and I’d be happy to contribute.

Kindly assign it to me if it’s available. Thank you!