fix: Restore all files lost during destructive rebase

A previous `git pull --rebase origin main` dropped 177 local commits,
losing 3400+ files across admin-v2, backend, studio-v2, website,
klausur-service, and many other services. The partial restore attempt
(660295e2) only recovered some files.

This commit restores all missing files from pre-rebase ref 98933f5e
while preserving post-rebase additions (night-scheduler, night-mode UI,
NightModeWidget dashboard integration).

Restored features include:
- AI Module Sidebar (FAB), OCR Labeling, OCR Compare
- GPU Dashboard, RAG Pipeline, Magic Help
- Klausur-Korrektur (8 files), Abitur-Archiv (5+ files)
- Companion, Zeugnisse-Crawler, Screen Flow
- Full backend, studio-v2, website, klausur-service
- All compliance SDKs, agent-core, voice-service
- CI/CD configs, documentation, scripts

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

klausur-service/backend/storage.py

@@ -0,0 +1,61 @@
+"""
+Klausur-Service In-Memory Storage
+
+Centralized storage for all in-memory data.
+Note: In production, this should be replaced with a database.
+"""
+
+from typing import Dict, List
+
+from models.exam import Klausur, StudentKlausur
+from models.grading import AuditLogEntry
+from models.eh import (
+    Erwartungshorizont,
+    EHRightsConfirmation,
+    EHAuditLogEntry,
+    EHKeyShare,
+    EHKlausurLink,
+    EHShareInvitation,
+)
+
+# =============================================
+# KLAUSUR STORAGE
+# =============================================
+
+# Klausur storage: klausur_id -> Klausur
+klausuren_db: Dict[str, Klausur] = {}
+
+# Student work storage: student_id -> StudentKlausur
+students_db: Dict[str, StudentKlausur] = {}
+
+# Examiner assignments: student_id -> examiner info
+examiner_db: Dict[str, Dict] = {}
+
+# =============================================
+# AUDIT LOG STORAGE
+# =============================================
+
+# General audit log
+audit_log_db: List[AuditLogEntry] = []
+
+# =============================================
+# BYOEH STORAGE
+# =============================================
+
+# Erwartungshorizont storage: eh_id -> Erwartungshorizont
+eh_db: Dict[str, Erwartungshorizont] = {}
+
+# Rights confirmations: confirmation_id -> EHRightsConfirmation
+eh_rights_db: Dict[str, EHRightsConfirmation] = {}
+
+# EH audit log
+eh_audit_db: List[EHAuditLogEntry] = []
+
+# Key shares: eh_id -> list of EHKeyShare
+eh_key_shares_db: Dict[str, List[EHKeyShare]] = {}
+
+# EH-Klausur links: klausur_id -> list of EHKlausurLink
+eh_klausur_links_db: Dict[str, List[EHKlausurLink]] = {}
+
+# Share invitations: invitation_id -> EHShareInvitation
+eh_invitations_db: Dict[str, EHShareInvitation] = {}