feat(canopy-tanf): per-row activity_breakdown drill-down on work-activity summary endpoint

Source: canopy-tanf-work-activities-list plan Potential Improvements.

Today GET /v1/work-activities/summary aggregates hours by activity_type (one row per distinct type). Auditors resolving an ACF-199 discrepancy need the ability to drill down to per-work_activity_id rows so a flagged hour count can be traced back to the individual logged record. Useful when the same person has overlapping employment entries with different effective_date ranges in the same month.

Acceptance: ?detail=row query param on the summary endpoint emits a per-row breakdown payload; existing aggregated payload remains the default for backwards compatibility.