feat: add export options to the report and add testing suite

[patelheet30]

Summary

Adds JSON and CSV export capabilities for programmatic use and spreadsheet analysis.

New Features

✅ JSON Export

• Structured JSON output with shape, issue count, and detailed issues
• Each issue includes: check type, column, severity, message
• Use in APIs, data pipelines, or automated workflows

✅ CSV Export

• Spreadsheet-friendly CSV format
• Easy to import into Excel or Google Sheets
• Columns: check, column, severity, message

✅ Dictionary Output

• return_dict=True for Python dictionary
• Perfect for programmatic use in scripts

Usage Examples

# JSON export
df.lint.report(report_format='json', output='report.json')

# CSV export  
df.lint.report(report_format='csv', output='issues.csv')

# Get Python dict
data = df.lint.report(return_dict=True)
print(data['issue_count'])

# All formats support specific checks
df.lint.report(
    report_format='json',
    checks_to_run=['missing', 'duplicates'],
    output='focused.json'
)

Documentation

• CHANGELOG.md updated
• README.md roadmap completed
• Method docstrings updated

Breaking Changes

None - fully backward compatible

Related

Part 3 of v0.7.0 development. Completes v0.7.0 feature set!

[Copilot]

Pull request overview

This PR adds JSON and CSV export capabilities to the LintData reporting system, enabling programmatic use and spreadsheet analysis. The implementation includes comprehensive test coverage and maintains backward compatibility with existing text and HTML formats.

Key Changes

• Added JSON, CSV, and dictionary output formats to the report() method
• Implemented structured data parsing from warning strings with severity classification
• Added comprehensive test suite with 30+ tests covering all export formats and edge cases

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
tests/test_export.py	New test file with comprehensive coverage for JSON, CSV, and dict exports including edge cases
src/lintdata/accessor.py	Extended report() method with new formats and added helper methods for parsing/formatting warnings
README.md	Updated roadmap to mark export options as complete
CHANGELOG.md	Documented new export features and helper methods

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 10 comments.

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