Stundenplan Phase 3b: 3 more Stammdaten managers, first constraint editor, full test coverage

Frontend additions in studio-v2:
  - LehrerManager / FaecherManager / RaeumeManager — same CRUD pattern as
    Klassen, with entity-specific form fields and table columns.
  - regeln/TeacherUnavailableDayEditor — first constraint editor, joins
    against teachersApi to render a readable name in the dropdown and
    list. Falls back to a guidance banner when no teachers exist yet.
  - page.tsx wires up the new tabs; data-testid attributes added across
    managers so the Playwright suite can target them deterministically.

Tests:
  - school-service: timetable_constraints_more_test.go fills the
    remaining 9 constraint DTOs (TeacherMaxHoursDay/Week,
    TeacherExcludedSubject/Room, SubjectMinDayGap,
    SubjectContiguousWhenRepeated, SubjectDoubleLesson, ClassNoGaps,
    RoomRequiresType). 66 subtests total, all green.
  - studio-v2: e2e/stundenplan.spec.ts covers the page shell, tab
    navigation, Klassen CRUD with mocked backend, constraint editor's
    empty-teacher fallback, sidebar entry. All school-service calls
    intercepted via page.route() so the suite is hermetic.

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

studio-v2/app/stundenplan/page.tsx

@@ -6,6 +6,10 @@ import { Sidebar } from '@/components/Sidebar'
 import { ThemeToggle } from '@/components/ThemeToggle'
 import { LanguageDropdown } from '@/components/LanguageDropdown'
 import { KlassenManager } from './_components/KlassenManager'
+import { LehrerManager } from './_components/LehrerManager'
+import { FaecherManager } from './_components/FaecherManager'
+import { RaeumeManager } from './_components/RaeumeManager'
+import { TeacherUnavailableDayEditor } from './_components/regeln/TeacherUnavailableDayEditor'
 import { setStundenplanToken, getStundenplanToken } from '@/lib/stundenplan/api'
 
 type Tab = 'klassen' | 'lehrer' | 'faecher' | 'raeume' | 'periods' | 'curriculum' | 'assignments' | 'regeln'
@@ -102,15 +106,20 @@ export default function StundenplanPage() {
 
         <section>
           {tab === 'klassen' && <KlassenManager />}
-          {tab !== 'klassen' && (
+          {tab === 'lehrer' && <LehrerManager />}
+          {tab === 'faecher' && <FaecherManager />}
+          {tab === 'raeume' && <RaeumeManager />}
+          {tab === 'regeln' && <TeacherUnavailableDayEditor />}
+          {(tab === 'periods' || tab === 'curriculum' || tab === 'assignments') && (
             <div
               className={`rounded-2xl border backdrop-blur-xl p-8 text-center ${
                 isDark ? 'bg-white/5 border-white/10 text-white/60' : 'bg-white/80 border-black/10 text-slate-500'
               }`}
+              data-testid="not-implemented"
             >
               <p className="text-lg">Noch nicht implementiert: {TABS.find(t => t.id === tab)?.label}</p>
               <p className="text-sm mt-2">
-                Das Klassen-Modul ist der Prototyp. Die anderen Stammdaten und alle 15 Constraints folgen dem gleichen Muster.
+                Folgt dem gleichen Muster wie Klassen / Lehrer / Faecher / Raeume.
               </p>
             </div>
           )}