Add timetable scheduler Phases 1 + 2 to school-service

Phase 1 — Stammdaten (7 tables):
  tt_class, tt_period, tt_room, tt_subject, tt_teacher,
  tt_curriculum, tt_assignment with CRUD endpoints.

Phase 2 — Constraints (15 typed tables):
  Teacher (6): unavailable_day, unavailable_window, max_hours_day,
    max_hours_week, excluded_subject, excluded_room
  Subject (5): min_day_gap, max_consecutive, contiguous_when_repeated,
    preferred_period, double_lesson
  Class (2): max_hours_day, no_gaps
  Room (2): requires_type, unavailable

Each constraint row carries is_hard / weight / active / note /
created_by_user_id; ownership enforced via WHERE EXISTS against the
parent tt_teacher/tt_class/tt_subject/tt_room row.

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

school-service/internal/handlers/handlers.go

@@ -16,6 +16,7 @@ type Handler struct {
 	gradebookService   *services.GradebookService
 	certificateService *services.CertificateService
 	aiService          *services.AIService
+	timetableService   *services.TimetableService
 }
 
 // NewHandler creates a new Handler with all services
@@ -26,6 +27,7 @@ func NewHandler(db *pgxpool.Pool, llmGatewayURL string) *Handler {
 	gradebookService := services.NewGradebookService(db)
 	certificateService := services.NewCertificateService(db, gradeService, gradebookService)
 	aiService := services.NewAIService(llmGatewayURL)
+	timetableService := services.NewTimetableService(db)
 
 	return &Handler{
 		classService:       classService,
@@ -34,6 +36,7 @@ func NewHandler(db *pgxpool.Pool, llmGatewayURL string) *Handler {
 		gradebookService:   gradebookService,
 		certificateService: certificateService,
 		aiService:          aiService,
+		timetableService:   timetableService,
 	}
 }