feat(academy): bridge Academy with Training Engine for course generation

- Add POST /academy/courses/generate endpoint that creates an academy
  course from a training module (with content + quiz as lessons)
- Add POST /academy/courses/generate-all to bulk-generate all courses
- Fix academy API response mapping (snake_case → camelCase)
- Fix fetchCourses/fetchCourse/fetchEnrollments/fetchStats to unwrap
  backend response wrappers ({courses:[...]}, {course:{...}})
- Add "Alle Kurse generieren" button to academy overview page
- Fix bulkResult.errors crash in training page (optional chaining)
- Add SetAcademyCourseID to training store for bidirectional linking

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin-compliance/app/(sdk)/sdk/training/page.tsx

@@ -132,7 +132,7 @@ export default function TrainingPage() {
     setBulkResult(null)
     try {
       const result = await generateAllContent('de')
-      setBulkResult(result)
+      setBulkResult({ generated: result.generated ?? 0, skipped: result.skipped ?? 0, errors: result.errors ?? [] })
       await loadData()
     } catch (e) {
       setError(e instanceof Error ? e.message : 'Fehler bei der Bulk-Generierung')
@@ -155,7 +155,7 @@ export default function TrainingPage() {
     setBulkResult(null)
     try {
       const result = await generateAllQuizzes()
-      setBulkResult(result)
+      setBulkResult({ generated: result.generated ?? 0, skipped: result.skipped ?? 0, errors: result.errors ?? [] })
       await loadData()
     } catch (e) {
       setError(e instanceof Error ? e.message : 'Fehler bei der Bulk-Quiz-Generierung')
@@ -475,11 +475,11 @@ export default function TrainingPage() {
                 <div className="flex gap-6">
                   <span className="text-green-700">Generiert: {bulkResult.generated}</span>
                   <span className="text-gray-500">Uebersprungen: {bulkResult.skipped}</span>
-                  {bulkResult.errors.length > 0 && (
+                  {bulkResult.errors?.length > 0 && (
                     <span className="text-red-600">Fehler: {bulkResult.errors.length}</span>
                   )}
                 </div>
-                {bulkResult.errors.length > 0 && (
+                {bulkResult.errors?.length > 0 && (
                   <div className="mt-2 text-xs text-red-600">
                     {bulkResult.errors.map((err, i) => <div key={i}>{err}</div>)}
                   </div>