[split-required] Split 500-1000 LOC files across all services

backend-lehrer (5 files):
- alerts_agent/db/repository.py (992 → 5), abitur_docs_api.py (956 → 3)
- teacher_dashboard_api.py (951 → 3), services/pdf_service.py (916 → 3)
- mail/mail_db.py (987 → 6)

klausur-service (5 files):
- legal_templates_ingestion.py (942 → 3), ocr_pipeline_postprocess.py (929 → 4)
- ocr_pipeline_words.py (876 → 3), ocr_pipeline_ocr_merge.py (616 → 2)
- KorrekturPage.tsx (956 → 6)

website (5 pages):
- mail (985 → 9), edu-search (958 → 8), mac-mini (950 → 7)
- ocr-labeling (946 → 7), audit-workspace (871 → 4)

studio-v2 (5 files + 1 deleted):
- page.tsx (946 → 5), MessagesContext.tsx (925 → 4)
- korrektur (914 → 6), worksheet-cleanup (899 → 6)
- useVocabWorksheet.ts (888 → 3)
- Deleted dead page-original.tsx (934 LOC)

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

klausur-service/backend/mail/mail_db_stats.py

@@ -0,0 +1,118 @@
+"""
+Mail Database - Statistics and Audit Log Operations.
+"""
+
+import json
+import uuid
+from typing import Optional, Dict
+from datetime import datetime
+
+from .mail_db_pool import get_pool
+
+
+async def get_mail_stats(user_id: str) -> Dict:
+    """Get overall mail statistics for a user."""
+    pool = await get_pool()
+    if pool is None:
+        return {}
+
+    try:
+        async with pool.acquire() as conn:
+            today = datetime.now().replace(hour=0, minute=0, second=0, microsecond=0)
+
+            # Account stats
+            accounts = await conn.fetch(
+                """
+                SELECT id, email, display_name, status, email_count, unread_count, last_sync
+                FROM external_email_accounts
+                WHERE user_id = $1
+                """,
+                user_id
+            )
+
+            # Email counts
+            email_stats = await conn.fetchrow(
+                """
+                SELECT
+                    COUNT(*) as total_emails,
+                    COUNT(*) FILTER (WHERE is_read = FALSE) as unread_emails,
+                    COUNT(*) FILTER (WHERE date_received >= $2) as emails_today,
+                    COUNT(*) FILTER (WHERE ai_analyzed_at >= $2) as ai_analyses_today
+                FROM aggregated_emails
+                WHERE user_id = $1
+                """,
+                user_id, today
+            )
+
+            # Task counts
+            task_stats = await conn.fetchrow(
+                """
+                SELECT
+                    COUNT(*) as total_tasks,
+                    COUNT(*) FILTER (WHERE status = 'pending') as pending_tasks,
+                    COUNT(*) FILTER (WHERE status != 'completed' AND deadline < NOW()) as overdue_tasks
+                FROM inbox_tasks
+                WHERE user_id = $1
+                """,
+                user_id
+            )
+
+            return {
+                "total_accounts": len(accounts),
+                "active_accounts": sum(1 for a in accounts if a['status'] == 'active'),
+                "error_accounts": sum(1 for a in accounts if a['status'] == 'error'),
+                "total_emails": email_stats['total_emails'] or 0,
+                "unread_emails": email_stats['unread_emails'] or 0,
+                "total_tasks": task_stats['total_tasks'] or 0,
+                "pending_tasks": task_stats['pending_tasks'] or 0,
+                "overdue_tasks": task_stats['overdue_tasks'] or 0,
+                "emails_today": email_stats['emails_today'] or 0,
+                "ai_analyses_today": email_stats['ai_analyses_today'] or 0,
+                "per_account": [
+                    {
+                        "id": a['id'],
+                        "email": a['email'],
+                        "display_name": a['display_name'],
+                        "status": a['status'],
+                        "email_count": a['email_count'],
+                        "unread_count": a['unread_count'],
+                        "last_sync": a['last_sync'].isoformat() if a['last_sync'] else None,
+                    }
+                    for a in accounts
+                ],
+            }
+    except Exception as e:
+        print(f"Failed to get mail stats: {e}")
+        return {}
+
+
+async def log_mail_audit(
+    user_id: str,
+    action: str,
+    entity_type: Optional[str] = None,
+    entity_id: Optional[str] = None,
+    details: Optional[Dict] = None,
+    tenant_id: Optional[str] = None,
+    ip_address: Optional[str] = None,
+    user_agent: Optional[str] = None,
+) -> bool:
+    """Log a mail action for audit trail."""
+    pool = await get_pool()
+    if pool is None:
+        return False
+
+    try:
+        async with pool.acquire() as conn:
+            await conn.execute(
+                """
+                INSERT INTO mail_audit_log
+                (id, user_id, tenant_id, action, entity_type, entity_id, details, ip_address, user_agent)
+                VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
+                """,
+                str(uuid.uuid4()), user_id, tenant_id, action, entity_type, entity_id,
+                json.dumps(details) if details else None, ip_address, user_agent
+            )
+        return True
+    except Exception as e:
+        print(f"Failed to log mail audit: {e}")
+        return False