feat(customer): allow changing an already-registered NetBird API token

The per-customer Auto-Updates card only showed the token input when no
token was registered yet, so there was no way to replace one once set
(e.g. rotating it manually). Adds a "Change token" link that reveals the
same input/save flow at any time.

static/js/app.js

@@ -625,12 +625,27 @@ async function loadCustomerNetbirdUpdates(id, hasToken) {
                     <button class="btn btn-outline-secondary btn-sm" onclick="syncCustomerNetbirdFromMaster(${id})">${t('customer.nbuSyncMaster')}</button>
                 </div>
             </div>
-            <div id="nbu-result" class="small mt-2"></div>`;
+            <div id="nbu-result" class="small mt-2"></div>
+            <div class="mt-2">
+                <a href="#" class="small" onclick="event.preventDefault(); showChangeNetbirdToken(${id})">${t('customer.nbuChangeToken')}</a>
+            </div>
+            <div id="nbu-change-token-area" class="mt-2 d-none"></div>`;
     } catch (err) {
         container.innerHTML = `<div class="alert alert-warning py-2 small mb-0">${esc(err.message)}</div>`;
     }
 }
 
+function showChangeNetbirdToken(id) {
+    const area = document.getElementById('nbu-change-token-area');
+    area.classList.remove('d-none');
+    area.innerHTML = `
+        <div class="input-group input-group-sm">
+            <input type="text" class="form-control" id="nbu-token-input" placeholder="${t('customer.nbuTokenPlaceholder')}">
+            <button class="btn btn-outline-primary" onclick="saveCustomerNetbirdToken(${id})">${t('customer.nbuSaveToken')}</button>
+        </div>
+        <div id="nbu-token-result" class="small mt-1"></div>`;
+}
+
 async function saveCustomerNetbirdToken(id) {
     const input = document.getElementById('nbu-token-input');
     const resultEl = document.getElementById('nbu-token-result');

static/lang/de.json

@@ -97,6 +97,7 @@
     "nbuTokenPlaceholder": "Personal Access Token einfügen…",
     "nbuSaveToken": "Prüfen & Speichern",
     "nbuTokenSaved": "Token gespeichert.",
+    "nbuChangeToken": "Token ändern",
     "nbuVersion": "Client-Version",
     "nbuDisabled": "Deaktiviert",
     "nbuLatest": "Neueste Version",

static/lang/en.json

@@ -97,6 +97,7 @@
     "nbuTokenPlaceholder": "Paste Personal Access Token…",
     "nbuSaveToken": "Verify & Save",
     "nbuTokenSaved": "Token saved.",
+    "nbuChangeToken": "Change token",
     "nbuVersion": "Client version",
     "nbuDisabled": "Disabled",
     "nbuLatest": "Latest version",