Phase 9b: Schul-Events CRUD + Schuljahres-Rollover

Backend (school-service):
  - calendar_events.go — Create/List/Delete on cal_school_event with
    UUID[] handling for affected_class_ids. Default lead-days [7,1]
    if caller omits the array.
  - calendar_rollover.go — single-transaction promotion: graduating
    classes (grade >= 13) get deleted first so the +1 update doesn't
    bump them to invalid grade 14. defaultSchoolYearDates() picks the
    next Aug-Jul pair when the caller doesn't specify.
  - Handlers + routes: GET/POST /calendar/events,
    DELETE /calendar/events/:id, POST /calendar/school-year-rollover.

Frontend (studio-v2):
  - EventModal: form with Title / Typ / Datum/Zeit / unterrichtsfrei /
    Beschreibung / Sichtbarkeit + Notification-Checkboxen. Per-Type
    Farb-Mapping in types.ts.
  - DayDetail: Modal das beim Klick auf einen Kalender-Tag aufgeht und
    Feiertage + Schulferien + Schul-Events fuer diesen Tag listet,
    inkl. Loeschen-Button pro Event.
  - RolloverWizard: zwei-Schritt-Dialog mit Datums-Auswahl + Tipp-
    Bestaetigung ("SCHULJAHR WECHSELN") gegen versehentliche Auslo-
    sung, danach Ergebnis-Card mit promoted/graduated-Counts.
  - MonthView gewinnt onDayClick + onAddEvent + onRollover Props,
    rendert farb-codierte Punkte fuer School-Events am Tagesrand.
  - Page laed Events parallel mit Holidays und reicht alle Handler
    nach unten.

Tests:
  - Go: 3 neue Tests fuer defaultSchoolYearDates + parseClassIDs.
    Validator-Test fuer CreateSchoolEventRequest existiert bereits.
    80 Subtests gesamt, alle gruen.
  - Playwright: mockCalendarApi gewinnt Routes fuer events GET/POST/
    DELETE und school-year-rollover. 6 neue Tests (EventModal open,
    submit, DayDetail open, Rollover-Trigger, Confirm-Schutz,
    Ergebnis-Anzeige).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

school-service/internal/services/calendar_events.go

@@ -0,0 +1,134 @@
+package services
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/breakpilot/school-service/internal/models"
+	"github.com/google/uuid"
+)
+
+// School-event CRUD. Ownership is per-user via created_by_user_id. Public
+// holiday/Ferien data lives in cal_public_event and is handled by
+// calendar_service.go.
+
+func (s *CalendarService) CreateEvent(ctx context.Context, userID string, req *models.CreateSchoolEventRequest) (*models.SchoolEvent, error) {
+	classIDs, err := parseClassIDs(req.AffectedClassIDs)
+	if err != nil {
+		return nil, err
+	}
+
+	var e models.SchoolEvent
+	leadDays := req.NotificationLeadDays
+	if leadDays == nil {
+		leadDays = []int{7, 1}
+	}
+
+	row := s.db.QueryRow(ctx, `
+		INSERT INTO cal_school_event
+		  (created_by_user_id, title, description, event_type, is_school_free,
+		   start_date, end_date, start_time, end_time, affected_class_ids,
+		   visible_to_parents, notify_parents, notify_students, notification_lead_days)
+		VALUES ($1, $2, $3, $4, $5,
+		        $6::date, $7::date, NULLIF($8, '')::time, NULLIF($9, '')::time,
+		        $10, $11, $12, $13, $14)
+		RETURNING id, created_by_user_id, title, COALESCE(description,''), event_type,
+		          is_school_free, start_date::text, end_date::text,
+		          start_time::text, end_time::text, affected_class_ids,
+		          visible_to_parents, notify_parents, notify_students,
+		          notification_lead_days, created_at, updated_at
+	`, userID, req.Title, req.Description, req.EventType, req.IsSchoolFree,
+		req.StartDate, req.EndDate, strOrEmpty(req.StartTime), strOrEmpty(req.EndTime),
+		classIDs, req.VisibleToParents, req.NotifyParents, req.NotifyStudents, leadDays)
+
+	if err := scanEvent(row, &e); err != nil {
+		return nil, err
+	}
+	return &e, nil
+}
+
+func (s *CalendarService) ListEvents(ctx context.Context, userID, from, to string) ([]models.SchoolEvent, error) {
+	if from == "" {
+		from = "1900-01-01"
+	}
+	if to == "" {
+		to = "2100-12-31"
+	}
+	rows, err := s.db.Query(ctx, `
+		SELECT id, created_by_user_id, title, COALESCE(description,''), event_type,
+		       is_school_free, start_date::text, end_date::text,
+		       start_time::text, end_time::text, affected_class_ids,
+		       visible_to_parents, notify_parents, notify_students,
+		       notification_lead_days, created_at, updated_at
+		FROM cal_school_event
+		WHERE created_by_user_id = $1
+		  AND end_date   >= $2::date
+		  AND start_date <= $3::date
+		ORDER BY start_date, start_time NULLS FIRST, title
+	`, userID, from, to)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var out []models.SchoolEvent
+	for rows.Next() {
+		var e models.SchoolEvent
+		if err := scanEvent(rows, &e); err != nil {
+			return nil, err
+		}
+		out = append(out, e)
+	}
+	return out, nil
+}
+
+func (s *CalendarService) DeleteEvent(ctx context.Context, id, userID string) error {
+	res, err := s.db.Exec(ctx, `
+		DELETE FROM cal_school_event WHERE id = $1 AND created_by_user_id = $2
+	`, id, userID)
+	if err != nil {
+		return err
+	}
+	if res.RowsAffected() == 0 {
+		return fmt.Errorf("event not found or not owned")
+	}
+	return nil
+}
+
+// parseClassIDs validates the array of UUID strings the request sent.
+// Returns a typed []uuid.UUID so asyncpg/pgx encodes it correctly into the
+// UUID[] column.
+func parseClassIDs(in []string) ([]uuid.UUID, error) {
+	out := make([]uuid.UUID, 0, len(in))
+	for _, s := range in {
+		if s == "" {
+			continue
+		}
+		u, err := uuid.Parse(s)
+		if err != nil {
+			return nil, fmt.Errorf("invalid class_id %q: %w", s, err)
+		}
+		out = append(out, u)
+	}
+	return out, nil
+}
+
+// row interface so the same scan logic works for both QueryRow and Rows.
+type rowScanner interface {
+	Scan(dest ...any) error
+}
+
+func scanEvent(r rowScanner, e *models.SchoolEvent) error {
+	var startTime, endTime *string
+	if err := r.Scan(
+		&e.ID, &e.CreatedByUserID, &e.Title, &e.Description, &e.EventType,
+		&e.IsSchoolFree, &e.StartDate, &e.EndDate,
+		&startTime, &endTime, &e.AffectedClassIDs,
+		&e.VisibleToParents, &e.NotifyParents, &e.NotifyStudents,
+		&e.NotificationLeadDays, &e.CreatedAt, &e.UpdatedAt,
+	); err != nil {
+		return err
+	}
+	e.StartTime = startTime
+	e.EndTime = endTime
+	return nil
+}