fix(maintenance): auto-expiry + adaptive markdown height + tests

- Auto-expiry: expired events auto-end on GET /events via task manager
- Height: _estimate_markdown_height adapted to unit=8px scale with padding detection
- CRITICAL-1: removed dead import remove_chart_from_position (QA finding)
- CRITICAL-2: added chart alive check in ensure_banner_chart (QA finding)
- CRITICAL-3: fixed test assertions update_markdown_chart → update_banner_on_dashboard
- @POST contract: fixed return range [2,12] → [19,200]
- Tests: 8 new tests (auto-expiry + layout height)

docker-compose.enterprise-clean.yml

@@ -51,10 +51,8 @@ services:
     ports:
       - "${BACKEND_HOST_PORT:-8001}:8000"
     volumes:
-      - ./config.json:/app/config.json:ro
-      - ./backups:/app/backups
-      - ./backend/git_repos:/app/backend/git_repos
-      - ${STORAGE_ROOT:-./storage}:/app/storage
+      # Единая точка хранения: бэкапы → /app/storage/backups/, git-repos → /app/storage/repositories/, LLM-скриншоты → /app/storage/screenshots/
+      - ./storage:/app/storage
       # Корпоративные CA-сертификаты (.crt файлы). Монтируются в /opt/certs,
       # entrypoint.sh установит их в системное хранилище доверия.
       - ${CERTS_PATH:-./certs}:/opt/certs:ro