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/handlers/calendar_handlers.go

@@ -74,3 +74,72 @@ func (h *Handler) UpsertCalendarConfig(c *gin.Context) {
 	}
 	respondCreated(c, cfg)
 }
+
+// ---------- School Events (Phase 9b) ----------
+
+func (h *Handler) CreateSchoolEvent(c *gin.Context) {
+	uid := getUserID(c)
+	if uid == "" {
+		respondError(c, http.StatusUnauthorized, "User not authenticated")
+		return
+	}
+	var req models.CreateSchoolEventRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		respondError(c, http.StatusBadRequest, "Invalid request: "+err.Error())
+		return
+	}
+	ev, err := h.calendarService.CreateEvent(c.Request.Context(), uid, &req)
+	if err != nil {
+		respondError(c, http.StatusInternalServerError, "Failed to create event: "+err.Error())
+		return
+	}
+	respondCreated(c, ev)
+}
+
+func (h *Handler) ListSchoolEvents(c *gin.Context) {
+	uid := getUserID(c)
+	if uid == "" {
+		respondError(c, http.StatusUnauthorized, "User not authenticated")
+		return
+	}
+	events, err := h.calendarService.ListEvents(c.Request.Context(), uid, c.Query("from"), c.Query("to"))
+	if err != nil {
+		respondError(c, http.StatusInternalServerError, "Failed to list events: "+err.Error())
+		return
+	}
+	if events == nil {
+		events = []models.SchoolEvent{}
+	}
+	respondSuccess(c, events)
+}
+
+func (h *Handler) DeleteSchoolEvent(c *gin.Context) {
+	uid := getUserID(c)
+	if uid == "" {
+		respondError(c, http.StatusUnauthorized, "User not authenticated")
+		return
+	}
+	if err := h.calendarService.DeleteEvent(c.Request.Context(), c.Param("id"), uid); err != nil {
+		respondError(c, http.StatusInternalServerError, "Failed to delete event: "+err.Error())
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"message": "Event deleted"})
+}
+
+func (h *Handler) RolloverSchoolYear(c *gin.Context) {
+	uid := getUserID(c)
+	if uid == "" {
+		respondError(c, http.StatusUnauthorized, "User not authenticated")
+		return
+	}
+	var req models.SchoolYearRolloverRequest
+	// Body is optional — empty defaults to next-Aug rollover.
+	_ = c.ShouldBindJSON(&req)
+
+	result, err := h.calendarService.RolloverSchoolYear(c.Request.Context(), uid, &req)
+	if err != nil {
+		respondError(c, http.StatusInternalServerError, "Rollover failed: "+err.Error())
+		return
+	}
+	respondSuccess(c, result)
+}