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/app/core/dependencies.py

@@ -4,7 +4,7 @@ from uuid import UUID
 
 from fastapi import Depends, HTTPException, Request, status
 from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
-from jose import JWTError
+from jwt import PyJWTError as JWTError
 from sqlalchemy import text
 from sqlalchemy.ext.asyncio import AsyncSession
 

backend/app/core/security.py

@@ -4,7 +4,8 @@ import secrets
 import hashlib
 
 import bcrypt
-from jose import JWTError, jwt
+import jwt
+from jwt import PyJWTError as JWTError
 
 from app.core.config import settings
 

backend/app/routers/auth.py

@@ -306,7 +306,7 @@ async def totp_login(
     from app.core.config import settings
     from app.core.security import decode_partial_token
     from app.models.user import User
-    from jose import JWTError
+    from jwt import PyJWTError as JWTError
 
     try:
         user_id = decode_partial_token(data.partial_token)