Hub-and-Spoke Umbau: Multi-Tenant Zentrale + Satellite-Agent

- Backend: Customer/Satellite Models, customer_id auf Server/Job/Audit
- Satellite-API: heartbeat, poll (atomares Claiming), logs, result,
  scan-result, health-report - Auth via X-Api-Key (SHA-256 gehasht)
- Job-Queue: pending/claimed/running/success/failed + Stale-Janitor
- Batch-Trigger: ein Job pro Server, Satellite arbeitet sequenziell ab
- Credentials bleiben lokal: nur symbolische credential_ref zentral
- Neues Paket satellite/: Pull-Loop, WinRM/SSH/CAU/Scanner, PyInstaller-tauglich
- Frontend: Kunden-Switcher, Satelliten-View, Polling statt WebSocket
- Entfernt: WebSocket/Socket.io, Redis, zentrale Credentials, JobRunner
- Docs: README/AGENTS/PROMPT auf neue Architektur aktualisiert

backend/pyproject.toml

@@ -11,16 +11,11 @@ dependencies = [
     "alembic>=1.13.0",
     "aiosqlite>=0.19.0",
     "asyncpg>=0.29.0",
-    "redis>=5.0.0",
     "python-jose[cryptography]>=3.3.0",
     "bcrypt>=4.1.0",
     "cryptography>=42.0.0",
     "pydantic[email]>=2.5.0",
     "pydantic-settings>=2.1.0",
-    "pywinrm[kerberos]>=0.4.3",
-    "paramiko>=3.4.0",
-    "asyncssh>=2.14.0",
-    "python-socketio>=5.10.0",
     "structlog>=24.1.0",
     "python-json-logger>=2.0.7",
     "python-multipart>=0.0.6",