feat(260923-dhh): Proxmox-Modul Aufgabe 5 - Einstellungsseite (anlegen, bearbeiten, loeschen, testen)

- proxmox.service.ts: updateServer (Muster LdapConfigService.updateConfig
  - nicht gesendet laesst unveraendert, leer loescht, gefuellt
  verschluesselt neu; PMG+Token auch beim Bearbeiten abgelehnt, geprueft
  gegen den EFFEKTIVEN Stand nach Zusammenfuehren), deleteServer
- proxmox.controller.ts: PUT/DELETE servers/:id, beide zusaetzlich mit
  scheduler.refreshTenant() nach dem Schreiben
- Frontend: proxmox-api.ts (updateServer/deleteServer/testServer),
  settings/page.tsx (Rollenpruefung nur Anzeige, Serverliste,
  Loeschen mit Rueckfrage), ServerForm.tsx (PMG bietet Token gar nicht
  an, Geheimnisfelder nie vorbefuellt, Zertifikatspruefung-Schalter
  Standard "pruefen", Verbindungstest mit Klartext-Fehlertext)
- umlaut-dictionary.ts: zwei neue, bereits korrekte Woerter
  (bewusst/gemessene) auf die Positivliste des Regressions-Waechters

Tore: api 1311/1311 (>=1240), web 701/701 (>=693), type-check 4/4,
lint 5/5, Biome apps/web 53 Warnungen (unveraendert).

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

apps/web/src/messages/en.json

@@ -708,7 +708,53 @@
     "description": "State of your Proxmox servers (PVE/PBS/PMG) at a glance — Tessera only observes, it never changes anything.",
     "loading": "Loading server list...",
     "loadError": "Could not load the server list.",
-    "emptyState": "No server configured yet. Add one in the module settings."
+    "emptyState": "No server configured yet. Add one in the module settings.",
+    "errors": {
+      "netz": "The server is unreachable. Please check the address and the network connection.",
+      "zugang": "Access was denied. Please check the username and password, or the token details.",
+      "rechte": "The stored account does not have enough rights. Please check the assigned role on the Proxmox server.",
+      "zertifikat": "The server's certificate was rejected. Check the address, or deliberately disable certificate checking for this one server.",
+      "antwortform": "The server's response did not have the expected shape. Please check the address.",
+      "server": "The Proxmox server reports its own error. Please try again later.",
+      "unbekannt": "An unexpected error occurred."
+    },
+    "settings": {
+      "title": "Proxmox — Settings",
+      "accessDeniedText": "This page is only available to administrators.",
+      "addServer": "Add server",
+      "noServers": "No server configured yet.",
+      "nameLabel": "Name",
+      "productTypeLabel": "Type",
+      "productTypePve": "PVE",
+      "productTypePbs": "PBS",
+      "productTypePmg": "PMG",
+      "baseUrlLabel": "Address",
+      "authMethodLabel": "Access method",
+      "authMethodToken": "API token",
+      "authMethodPassword": "Username/password",
+      "tokenIdLabel": "Token ID",
+      "tokenSecretLabel": "Token secret",
+      "usernameLabel": "Username",
+      "passwordLabel": "Password",
+      "secretUnchangedPlaceholder": "Leave blank to keep the stored secret",
+      "pollIntervalLabel": "Poll interval (minutes)",
+      "tlsRejectLabel": "Verify certificate",
+      "tlsRejectHint": "The exception applies only to this one server, never to all servers at once.",
+      "activeLabel": "Active",
+      "save": "Save",
+      "saving": "Saving...",
+      "saveError": "Could not save the settings.",
+      "cancel": "Cancel",
+      "testConnection": "Test connection",
+      "testTesting": "Testing connection...",
+      "testSuccess": "Connection successful.",
+      "edit": "Edit",
+      "delete": "Delete",
+      "deleteConfirmTitle": "Delete server",
+      "deleteConfirmBody": "Do you really want to delete the server \"{name}\"? The last measured status will be removed as well.",
+      "deleteConfirmButton": "Delete",
+      "deleteCancelButton": "Cancel"
+    }
   },
   "dkvFleet": {
     "pageTitle": "DKV Invoice",