fix(security): python-jose CVE-2024-33663 durch pyjwt ersetzt, Deps gepinnt

- security.py/dependencies.py/auth.py: jose -> pyjwt (unmaintained,
  Algorithm-Confusion-CVE). API-kompatibel (jwt.encode/decode gleich).
- requirements.txt: alle Versionen gepinnt (waren >=, jetzt == anhand
  aktueller 137-Installation) fuer reproduzierbare Deploys.
- nginx.conf: /docs + /openapi.json nur noch aus LAN erreichbar (waren
  oeffentlich, API-Struktur-Leak).

fail2ban auf 137+164 installiert (sshd + nginx-badbots + timemaster-auth
Jails), Configs nicht im Repo (Server-only, /etc/fail2ban/).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LTxkZEUdfgMxZvHPiZJ8bV

backend/requirements.txt

@@ -1,29 +1,29 @@
-fastapi>=0.110.0
-uvicorn[standard]>=0.27.0
-sqlalchemy[asyncio]>=2.0.0
-asyncpg>=0.29.0
-alembic>=1.13.0
-pydantic[email]>=2.6.0
-pydantic-settings>=2.2.0
-python-jose[cryptography]>=3.3.0
-bcrypt>=4.0.0
-openpyxl>=3.1.0
-ldap3>=2.9.0
-cryptography>=42.0.0
-python-multipart>=0.0.9
-slowapi>=0.1.9
-limits>=3.6.0
-redis>=5.0.0
-resend>=0.7.0
-python-dateutil>=2.9.0
-pyotp>=2.9.0
-httpx>=0.27.0
-icalendar>=5.0.0
-pytest>=8.0.0
-pytest-asyncio>=0.23.0
-pytest-httpx>=0.30.0
-aiosqlite>=0.20.0
-weasyprint>=61.0
-typer>=0.12.0
-rich>=13.7.0
-apscheduler>=3.10.0
+fastapi==0.135.2
+uvicorn[standard]==0.42.0
+sqlalchemy[asyncio]==2.0.48
+asyncpg==0.31.0
+alembic==1.18.4
+pydantic[email]==2.12.5
+pydantic-settings==2.13.1
+pyjwt[crypto]==2.10.1
+bcrypt==5.0.0
+openpyxl==3.1.5
+ldap3==2.9.1
+cryptography==46.0.6
+python-multipart==0.0.22
+slowapi==0.1.9
+limits==5.8.0
+redis==7.4.0
+resend==2.26.0
+python-dateutil==2.9.0.post0
+pyotp==2.9.0
+httpx==0.28.1
+icalendar==7.0.3
+pytest==9.0.2
+pytest-asyncio==1.3.0
+pytest-httpx==0.36.0
+aiosqlite==0.22.1
+weasyprint==68.1
+typer==0.25.1
+rich==15.0.0
+apscheduler==3.11.2