feat(reports): capacity-based utilization + report CSVs

Utilization now measures booked minutes against each member's
availability-rule capacity in the tenant timezone, replacing the
confirmed-share proxy. StaffMetric exposes booked/capacity minutes.

New endpoints: GET /v1/export/staff-report.csv (reuses StaffMetrics)
and GET /v1/export/service-report.csv (per-service bookings/cancelled/
revenue, class bookings rolled up). Export buttons on the staff
performance panel and services page.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/export/service.go

@@ -5,8 +5,10 @@ import (
 	"encoding/csv"
 	"errors"
 	"io"
+	"strconv"
 	"time"
 
+	"bookra/apps/backend/internal/bookings"
 	"bookra/apps/backend/internal/db"
 	"bookra/apps/backend/internal/domain"
 )
@@ -19,11 +21,12 @@ var utf8BOM = []byte{0xEF, 0xBB, 0xBF}
 const customerPageSize = 500
 
 type Service struct {
-	repo db.Repository
+	repo     db.Repository
+	bookings *bookings.Service
 }
 
-func NewService(repo db.Repository) *Service {
-	return &Service{repo: repo}
+func NewService(repo db.Repository, bookingsService *bookings.Service) *Service {
+	return &Service{repo: repo, bookings: bookingsService}
 }
 
 func (s *Service) tenantFor(ctx context.Context, principal domain.Principal) (db.TenantRecord, error) {
@@ -172,3 +175,126 @@ func (s *Service) WriteCustomersCSV(ctx context.Context, principal domain.Princi
 	}
 	return out.Error()
 }
+
+// WriteStaffReportCSV exports the per-staff performance metrics over a
+// trailing window — the same numbers the dashboard performance panel shows.
+func (s *Service) WriteStaffReportCSV(ctx context.Context, principal domain.Principal, w io.Writer, days int) error {
+	metrics, err := s.bookings.StaffMetrics(ctx, principal, days)
+	if err != nil {
+		if errors.Is(err, bookings.ErrTenantMembership) {
+			return ErrTenantMembership
+		}
+		return err
+	}
+
+	if _, err := w.Write(utf8BOM); err != nil {
+		return err
+	}
+	out := csv.NewWriter(w)
+	defer out.Flush()
+
+	if err := out.Write([]string{
+		"staff", "bookings", "completed", "cancelled",
+		"booked_minutes", "capacity_minutes", "utilization_percent", "revenue_cents",
+	}); err != nil {
+		return err
+	}
+	for _, m := range metrics.Staff {
+		if err := out.Write([]string{
+			m.DisplayName,
+			strconv.Itoa(m.Bookings),
+			strconv.Itoa(m.Completed),
+			strconv.Itoa(m.Cancelled),
+			strconv.Itoa(m.BookedMinutes),
+			strconv.Itoa(m.CapacityMinutes),
+			strconv.Itoa(m.UtilizationPercent),
+			strconv.FormatInt(m.RevenueCents, 10),
+		}); err != nil {
+			return err
+		}
+	}
+	return out.Error()
+}
+
+// WriteServiceReportCSV aggregates appointment bookings per catalog service
+// over a trailing window. Class bookings have no service or price and roll
+// into a final "class sessions" row when present.
+func (s *Service) WriteServiceReportCSV(ctx context.Context, principal domain.Principal, w io.Writer, days int) error {
+	tenant, err := s.tenantFor(ctx, principal)
+	if err != nil {
+		return err
+	}
+	if days <= 0 || days > 365 {
+		days = 30
+	}
+	to := time.Now().UTC()
+	from := to.AddDate(0, 0, -days)
+
+	bookingsList, err := s.repo.ListBookingsByTenantBetween(ctx, tenant.ID, from, to)
+	if err != nil {
+		return err
+	}
+	services, err := s.repo.ListServicesByTenant(ctx, tenant.ID)
+	if err != nil {
+		return err
+	}
+	prices := make(map[string]int, len(services))
+	for _, service := range services {
+		prices[service.ID] = service.PriceCents
+	}
+
+	type aggregate struct {
+		bookings  int
+		cancelled int
+		revenue   int64
+	}
+	byService := make(map[string]*aggregate, len(services))
+	classBookings := 0
+	for _, booking := range bookingsList {
+		if booking.ServiceID == nil {
+			classBookings++
+			continue
+		}
+		agg := byService[*booking.ServiceID]
+		if agg == nil {
+			agg = &aggregate{}
+			byService[*booking.ServiceID] = agg
+		}
+		agg.bookings++
+		if booking.Status == "cancelled" {
+			agg.cancelled++
+		} else {
+			agg.revenue += int64(prices[*booking.ServiceID])
+		}
+	}
+
+	if _, err := w.Write(utf8BOM); err != nil {
+		return err
+	}
+	out := csv.NewWriter(w)
+	defer out.Flush()
+
+	if err := out.Write([]string{"service", "bookings", "cancelled", "revenue_cents"}); err != nil {
+		return err
+	}
+	for _, service := range services {
+		agg := byService[service.ID]
+		if agg == nil {
+			agg = &aggregate{}
+		}
+		if err := out.Write([]string{
+			service.Name,
+			strconv.Itoa(agg.bookings),
+			strconv.Itoa(agg.cancelled),
+			strconv.FormatInt(agg.revenue, 10),
+		}); err != nil {
+			return err
+		}
+	}
+	if classBookings > 0 {
+		if err := out.Write([]string{"class sessions", strconv.Itoa(classBookings), "0", "0"}); err != nil {
+			return err
+		}
+	}
+	return out.Error()
+}