feat: email client prototype

frontend/app/src/assets/i18n/de.json

@@ -8,6 +8,7 @@
   "export": "Exportieren",
   "share": "Teilen",
   "timeSuffix": "Uhr",
+  "beta": "Beta",
   "ratings": {
     "thank_you": "Vielen Dank für die Bewertung!"
   },
@@ -386,6 +387,35 @@
       }
     }
   },
+  "mail": {
+    "SIGNATURE_VALID": "Signatur gültig",
+    "SIGNATURE_INVALID": "Signatur ungültig",
+    "SIGNATURE_UNSUPPORTED": "Signatur nicht unterstützt",
+    "ID": "ID",
+    "FROM": "von",
+    "SENDER": "Absender",
+    "TO": "an",
+    "DATE": "Datum",
+    "login": {
+      "TITLE": "E-Mail Login",
+      "LOGIN": "Login",
+      "PLACEHOLDER_USERNAME": "Nutzername",
+      "PLACEHOLDER_PASSWORD": "Passwort",
+      "error": {
+        "INVALID_CREDENTIALS": "ungültige Zugangsdaten"
+      }
+    },
+    "mailboxes": {
+      "\\Inbox": "Posteingang",
+      "\\All": "Alle",
+      "\\Archive": "Archiv",
+      "\\Drafts": "Entwürfe",
+      "\\Flagged": "Markiert",
+      "\\Junk": "Spam",
+      "\\Sent": "Gesendet",
+      "\\Trash": "Papierkorb"
+    }
+  },
   "menu": {
     "context": {
       "title": "Kontext Menü",