Phase 9a: Schulkalender — Bundesland-Auswahl + Monatsansicht mit Ferien

Backend (school-service):
  - cal_public_event (region, event_type, name_de, name_en, start/end,
    UNIQUE(region, event_type, name_de, start_date)) — global snapshot.
  - cal_school_config (user_id PRIMARY KEY, bundesland, school year dates).
  - cal_school_event — Schul-eigene Termine; CRUD folgt in 9b.
  - GET /calendar/holidays?region=&from=&to= — Range-Query against
    cal_public_event, ordered by start_date.
  - GET / PUT /calendar/config — upsert Bundesland per User.
  - SeedFromSnapshot reads internal/seed/calendar_holidays.json on every
    boot; idempotent via the unique constraint. Async goroutine so the
    HTTP server starts immediately even if the seed file is large.

Data source:
  - scripts/calendar-snapshot.sh ruft openholidaysapi.org fuer alle 16
    Bundeslaender x 3 Schuljahre und schreibt
    school-service/internal/seed/calendar_holidays.json (854 Events,
    Stand Schuljahre 2026-2028).
  - Dockerfile kopiert das seed/-Verzeichnis ins Image, damit die
    Container-Datenbank beim ersten Start gefuellt wird.

Frontend (studio-v2):
  - /schulkalender Page mit Gradient + Blobs wie /stundenplan und
    /korrektur — gleicher Visual-Style.
  - BundeslandWizard: zeigt alle 16 Laender als Dropdown, speichert
    bei Klick die Config und switcht zur Monatsansicht.
  - MonthView: 6-Wochen-Grid Mo-So, Feiertage rose-toned, Schulferien
    amber-toned, heutiges Datum mit Indigo-Ring. Prev/Next/Heute
    Navigation.
  - lib/schulkalender/api.ts re-uses the stundenplan JWT helper so
    auth-mode wechselt nicht.
  - Sidebar bekommt einen Schulkalender-Eintrag (Icon mit Datum-Dots,
    Pfad /schulkalender) in allen 26 Sprachen.

Tests:
  - Go: 3 neue Validator-Tests (Bundesland len=5, EventType oneof,
    Pflichtfelder). 77 Tests gesamt, alle gruen.
  - Playwright: e2e/schulkalender.spec.ts mit Wizard, Save-Flow,
    MonthView-Render, Heute-Button, Sidebar-Link. Hermetisch via
    mockCalendarApi.

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

school-service/internal/database/calendar_migrations.go

@@ -0,0 +1,69 @@
+package database
+
+// CalendarMigrations creates the three calendar tables for Phase 9a:
+//
+//   cal_public_event   — read-only snapshot of school holidays + public
+//                        holidays from OpenHolidaysAPI. Imported on first
+//                        boot via seed/calendar_holidays.json.
+//   cal_school_config  — per-Rektor bundesland selection (1 row per user).
+//   cal_school_event   — user-managed school events (Fortbildung,
+//                        Schulfeier, Klassenfahrt etc.).
+//
+// cal_public_event is global (no created_by_user_id) because the data is the
+// same for every school in a given bundesland. School-events are
+// per-tenant.
+func CalendarMigrations() []string {
+	return []string{
+		`CREATE TABLE IF NOT EXISTS cal_public_event (
+			id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+			region VARCHAR(8) NOT NULL,
+			event_type VARCHAR(20) NOT NULL CHECK (event_type IN ('public_holiday', 'school_holiday')),
+			name_de VARCHAR(255) NOT NULL,
+			name_en VARCHAR(255),
+			start_date DATE NOT NULL,
+			end_date DATE NOT NULL,
+			source VARCHAR(50) DEFAULT 'OpenHolidaysAPI',
+			created_at TIMESTAMPTZ DEFAULT NOW(),
+			UNIQUE(region, event_type, name_de, start_date),
+			CHECK (end_date >= start_date)
+		)`,
+
+		`CREATE TABLE IF NOT EXISTS cal_school_config (
+			user_id UUID PRIMARY KEY,
+			bundesland VARCHAR(8) NOT NULL,
+			school_year_start DATE,
+			school_year_end DATE,
+			created_at TIMESTAMPTZ DEFAULT NOW(),
+			updated_at TIMESTAMPTZ DEFAULT NOW()
+		)`,
+
+		`CREATE TABLE IF NOT EXISTS cal_school_event (
+			id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+			created_by_user_id UUID NOT NULL,
+			title VARCHAR(255) NOT NULL,
+			description TEXT,
+			event_type VARCHAR(30) NOT NULL
+				CHECK (event_type IN ('fortbildung','schulfeier','klassenfahrt','projekttag','eltern_info','andere')),
+			is_school_free BOOLEAN DEFAULT false,
+			start_date DATE NOT NULL,
+			end_date DATE NOT NULL,
+			start_time TIME,
+			end_time TIME,
+			affected_class_ids UUID[] DEFAULT '{}',
+			visible_to_parents BOOLEAN DEFAULT true,
+			notify_parents BOOLEAN DEFAULT false,
+			notify_students BOOLEAN DEFAULT false,
+			notification_lead_days INT[] DEFAULT '{7,1}',
+			created_at TIMESTAMPTZ DEFAULT NOW(),
+			updated_at TIMESTAMPTZ DEFAULT NOW(),
+			CHECK (end_date >= start_date)
+		)`,
+
+		// Indexes — public events are queried by region + date range. School
+		// events are queried by owner + date range.
+		`CREATE INDEX IF NOT EXISTS idx_cal_public_event_region_date
+		   ON cal_public_event(region, start_date, end_date)`,
+		`CREATE INDEX IF NOT EXISTS idx_cal_school_event_user_date
+		   ON cal_school_event(created_by_user_id, start_date, end_date)`,
+	}
+}

school-service/internal/database/database.go

@@ -221,6 +221,9 @@ func Migrate(db *DB) error {
 	// Append timetable solution migrations (see timetable_solution_migrations.go)
 	migrations = append(migrations, TimetableSolutionMigrations()...)
 
+	// Append calendar migrations (see calendar_migrations.go).
+	migrations = append(migrations, CalendarMigrations()...)
+
 	for _, migration := range migrations {
 		_, err := db.Pool.Exec(ctx, migration)
 		if err != nil {