Make email mandatory + sign in translations

app/models/user.rb

@@ -23,5 +23,6 @@ class User < ApplicationRecord
   normalizes :email_address, with: ->(e) { e.strip.downcase }
 
   validates :username, presence: true, uniqueness: true
+  validates :email_address, presence: true, uniqueness: true
   validates :lang, inclusion: { in: Languages::AVAILABLE_LANGUAGES.map { |lang| lang[:id] } }
 end

app/views/sessions/new.html.slim

@@ -4,10 +4,12 @@
       .form-floating
         = form.email_field :email_address, autocomplete: "username", required: true, autofocus: true, class: "form-control"
         = form.label :email_address, class: "required"
+          = t("activerecord.attributes.session.email_address")
   .row.mb-3
     .col
       .form-floating
         = form.password_field :password, autocomplete: "current-password", required: true, autofocus: true, class: "form-control", maxlength: 72
         = form.label :password, class: "required"
+          = t("activerecord.attributes.session.password")
 
-  = form.submit "Sign in"
+  = form.submit t("helpers.buttons.sign_in")