feat: email client prototype

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

@@ -7,6 +7,7 @@
   "back": "back",
   "export": "Export",
   "share": "Share",
+  "beta": "beta",
   "timeSuffix": "",
   "ratings": {
     "thank_you": "Thank you for your feedback!"
@@ -389,6 +390,35 @@
       }
     }
   },
+  "mail": {
+    "SIGNATURE_VALID": "signature valid",
+    "SIGNATURE_INVALID": "signature invalid",
+    "SIGNATURE_UNSUPPORTED": "signature unsupported",
+    "ID": "ID",
+    "FROM": "from",
+    "SENDER": "sender",
+    "TO": "to",
+    "DATE": "date",
+    "login": {
+      "TITLE": "email login",
+      "LOGIN": "login",
+      "PLACEHOLDER_USERNAME": "username",
+      "PLACEHOLDER_PASSWORD": "password",
+      "error": {
+        "INVALID_CREDENTIALS": "invalid credentials"
+      }
+    },
+    "mailboxes": {
+      "\\Inbox": "inbox",
+      "\\All": "all inboxes",
+      "\\Archive": "archive",
+      "\\Drafts": "drafts",
+      "\\Flagged": "flagged",
+      "\\Junk": "spam",
+      "\\Sent": "sent",
+      "\\Trash": "trash"
+    }
+  },
   "menu": {
     "context": {
       "title": "context menu",