feat(TRA-244): Reporting and CSV export for completion, progress, and quiz attempts
- CompletionReportView + CSV: enrollment-level completion status, filterable
by course_id, org_id, date_from, date_to
- ProgressReportView + CSV: page-level dwell-time aggregates, same filters
- AttemptReportView + CSV: quiz attempt scores, pass/fail, timestamps; org
filter joins through Enrollment.org_id; course filter traverses
quiz -> page -> lesson -> module -> course
- Streaming CSV responses with _EchoWriter to avoid buffering large exports
- pytest test suite covering filters, aggregation accuracy, and CSV format
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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