userpage: use form langfile, move login strings to common

login-related stuff was moved into common using the langmover script, so
that the user page doesn't have to use the admin language files.

lang/form/en-us.json

@@ -19,7 +19,8 @@
         "yourAccountIsValidUntil": "Your account will be valid until {date}.",
         "sendPIN": "Send the PIN below to the bot, then come back here to link your account.",
         "sendPINDiscord": "Type {command} in {server_channel} on Discord, then send the PIN below.",
-        "matrixEnterUser": "Enter your User ID, press submit, and a PIN will be sent to you. Enter it here to continue."
+        "matrixEnterUser": "Enter your User ID, press submit, and a PIN will be sent to you. Enter it here to continue.",
+        "welcomeUser": "Welcome, {user}"
     },
     "notifications": {
         "errorUserExists": "User already exists.",
@@ -59,4 +60,4 @@
             "plural": "Must have at least {n} special characters"
         }
     }
-}
+}