Initial commit: PoE Manager modern UI rebuild

- Neues, eigenständiges Frontend (Sidebar, zentriertes Logo in der Topbar,
  Dark/Light-Theme, Karten-Dashboard, Toasts/Modals statt Bootstrap)
- Oeffentliches Kurz-Dashboard ohne Login (Status-Uebersicht)
- Browser-SSH-Terminal (paramiko, plattformunabhaengig) zum Testen von
  Switch-Zugangsdaten inkl. interaktiver Host-Key-Bestaetigung
- Granulares Rechtesystem mit Gruppen (Devices/Switches-Berechtigungen)
- Aufgeraeumtes Backend mit konfigurierbaren Pfaden, auto-generierten
  Secrets statt hart codierter Werte im Original

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

etc/nginx/sites-available/poe_manager

@@ -0,0 +1,17 @@
+server {
+    listen 80;
+    server_name _;
+
+    location / {
+        proxy_pass http://127.0.0.1:5000;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+    }
+
+    location /static/ {
+        alias /srv/poe_manager/static/;
+        expires 7d;
+    }
+}

etc/systemd/system/poe_web.service

@@ -0,0 +1,16 @@
+[Unit]
+Description=PoE Manager Web App
+After=network.target
+
+[Service]
+Type=simple
+User=root
+WorkingDirectory=/srv/poe_manager
+# Nutze die virtuelle Umgebung
+ExecStart=/srv/poe_manager/venv/bin/python3 /srv/poe_manager/app.py
+Restart=always
+RestartSec=5
+
+[Install]
+WantedBy=multi-user.target
+

etc/systemd/system/rpi-check-restart.service

@@ -0,0 +1,6 @@
+[Unit]
+Description=Restart rpi-check.service
+
+[Service]
+Type=oneshot
+ExecStart=/bin/systemctl restart rpi-check.service

etc/systemd/system/rpi-check-restart.timer

@@ -0,0 +1,10 @@
+[Unit]
+Description=Restart RPI Check daily at 00:00
+
+[Timer]
+OnCalendar=*-*-* 00:00:00
+Persistent=true
+Unit=rpi-check-restart.service
+
+[Install]
+WantedBy=timers.target

etc/systemd/system/rpi-check.service

@@ -0,0 +1,14 @@
+[Unit]
+Description=RPI Ping Check
+After=network.target
+
+[Service]
+Type=simple
+User=root
+WorkingDirectory=/srv/poe_manager
+ExecStart=/srv/poe_manager/venv/bin/python3 /srv/poe_manager/poe_wrapper.py
+Restart=always
+RestartSec=5
+
+[Install]
+WantedBy=multi-user.target