Frontend: Add Custom Report Builder with Saved Report Templates

[Smartdevs17]

Context

Different stakeholders need different views of payment data. A fixed set of reports cannot satisfy diverse analytics requirements.

Current Limitation/Problem

Reports are predefined with fixed metrics and dimensions. Users cannot create custom reports or save report configurations for reuse.

Expected Outcome

A drag-and-drop report builder where users select metrics, dimensions, filters, and visualization types. Reports can be saved, scheduled, and shared.

Acceptance Criteria

• Visual report builder: select metrics (revenue, tx count, fees), dimensions (date, chain, currency, merchant), filters
• Chart type selection: line, bar, pie, table, heatmap, area
• Date range picker with relative presets (last 7d, 30d, this month, custom)
• Save report with name and description
• Report list with search, sort, and favorites
• Schedule report delivery via email (daily/weekly/monthly)
• Share report via link (view-only)
• Export as PDF, CSV, PNG
• Dashboard widget integration (pin to dashboard)

Technical Scope

• frontend/src/app/dashboard/reports/builder/ - report builder route
• frontend/src/components/reports/ - report components
• Zustand for report builder state
• backend/src/services/reports/custom-report.ts - report generation API
• Prisma: SavedReport, ScheduledReport, ReportTemplate models
• BullMQ for scheduled report generation
• Edge cases: empty results, very large datasets, chart rendering performance