[split-required] Split final batch of monoliths >1000 LOC

Python (6 files in klausur-service):
- rbac.py (1,132 → 4), admin_api.py (1,012 → 4)
- routes/eh.py (1,111 → 4), ocr_pipeline_geometry.py (1,105 → 5)

Python (2 files in backend-lehrer):
- unit_api.py (1,226 → 6), game_api.py (1,129 → 5)

Website (6 page files):
- 4x klausur-korrektur pages (1,249-1,328 LOC each) → shared components
  in website/components/klausur-korrektur/ (17 shared files)
- companion (1,057 → 10), magic-help (1,017 → 8)

All re-export barrels preserve backward compatibility.
Zero import errors verified.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

website/components/klausur-korrektur/StatistikenTab.tsx

@@ -0,0 +1,62 @@
+'use client'
+
+/**
+ * Statistics tab for the Klausur-Korrektur page.
+ * Shows summary cards and grade criteria info.
+ */
+
+import type { Klausur, GradeInfo } from '../../app/admin/klausur-korrektur/types'
+
+interface StatistikenTabProps {
+  klausuren: Klausur[]
+  gradeInfo: GradeInfo | null
+}
+
+export default function StatistikenTab({ klausuren, gradeInfo }: StatistikenTabProps) {
+  return (
+    <div className="space-y-6">
+      <h2 className="text-lg font-semibold text-slate-800">Korrektur-Statistiken</h2>
+
+      {/* Summary cards */}
+      <div className="grid grid-cols-1 md:grid-cols-4 gap-4">
+        <div className="bg-white rounded-lg border border-slate-200 p-4">
+          <div className="text-2xl font-bold text-slate-800">{klausuren.length}</div>
+          <div className="text-sm text-slate-500">Klausuren</div>
+        </div>
+        <div className="bg-white rounded-lg border border-slate-200 p-4">
+          <div className="text-2xl font-bold text-slate-800">
+            {klausuren.reduce((sum, k) => sum + (k.student_count || 0), 0)}
+          </div>
+          <div className="text-sm text-slate-500">Studentenarbeiten</div>
+        </div>
+        <div className="bg-white rounded-lg border border-slate-200 p-4">
+          <div className="text-2xl font-bold text-green-600">
+            {klausuren.reduce((sum, k) => sum + (k.completed_count || 0), 0)}
+          </div>
+          <div className="text-sm text-slate-500">Abgeschlossen</div>
+        </div>
+        <div className="bg-white rounded-lg border border-slate-200 p-4">
+          <div className="text-2xl font-bold text-orange-600">
+            {klausuren.reduce((sum, k) => sum + ((k.student_count || 0) - (k.completed_count || 0)), 0)}
+          </div>
+          <div className="text-sm text-slate-500">Ausstehend</div>
+        </div>
+      </div>
+
+      {/* Grade Info */}
+      {gradeInfo && (
+        <div className="bg-white rounded-lg border border-slate-200 p-6">
+          <h3 className="text-sm font-semibold text-slate-800 mb-4">Bewertungskriterien (Niedersachsen)</h3>
+          <div className="grid grid-cols-2 md:grid-cols-5 gap-4">
+            {Object.entries(gradeInfo.criteria || {}).map(([key, criterion]) => (
+              <div key={key} className="text-center p-3 bg-slate-50 rounded-lg">
+                <div className="text-lg font-semibold text-slate-700">{criterion.weight}%</div>
+                <div className="text-sm text-slate-500">{criterion.name}</div>
+              </div>
+            ))}
+          </div>
+        </div>
+      )}
+    </div>
+  )
+}