fix: Schluesselfeld sagt, dass BEGIN/END dazugehoeren

"Inhalt der .pem-Datei" liess offen, ob die Rahmenzeilen mitgehoeren. Sie
gehoeren dazu – ohne sie ist es kein gueltiges PEM und die Anbindung
scheitert schon vor der ersten Anfrage. Steht jetzt im Hinweis und im
Platzhalter.

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

web/src/locales/en.json

@@ -575,9 +575,9 @@
     "appReady": "Application configured",
     "appSaved": "Saved.",
     "applicationId": "Application ID",
-    "privateKey": "Private key (contents of the .pem file)",
+    "privateKey": "Private key – the entire .pem file",
     "privateKeyKeep": "Private key (leave empty to keep)",
-    "privateKeyHint": "Stored encrypted and never leaves the server. Every request to the bank is signed with it – treat it like a password.",
+    "privateKeyHint": "Open the file and paste everything, INCLUDING the “-----BEGIN PRIVATE KEY-----” and “-----END PRIVATE KEY-----” lines – without them it is not valid PEM. Stored encrypted, never leaves the server; every request to the bank is signed with it.",
     "baseUrl": "Public address of this installation",
     "baseUrlHint": "Must start with https:// and be reachable from outside – banks do not redirect to an unencrypted address. This address plus /bank/rueckkehr is what you register with Enable Banking.",
     "country": "Country of the bank",