mailer: send account emails as "asxp.io admin"

Invite and reset mails reused MAIL_FROM, whose display name is still
"IE Sergei Poljanski Contact Form" from the removed contact form. Keep
its verified address but use "asxp.io admin" as the name (overridable
with ADMIN_MAIL_NAME).

Assisted-by: Claude:opus-5

lib/mailer.rb

@@ -71,8 +71,16 @@ module Mailer
   end
 
   # Invite / password-reset email with a one-time link.
+  # Account mail keeps MAIL_FROM's verified address but not its display name
+  # ("… Contact Form"); ADMIN_MAIL_NAME overrides the default.
+  def admin_from
+    addr = Mail::Address.new(ENV.fetch('MAIL_FROM'))
+    addr.display_name = ENV.fetch('ADMIN_MAIL_NAME', 'asxp.io admin')
+    addr.format
+  end
+
   def account_link(to:, username:, url:, kind:)
-    from = ENV.fetch('MAIL_FROM')
+    from = admin_from
     subj, intro, ttl =
       if kind == 'invite'
         ['Your asxp.io admin account', "An account \"#{username}\" was created for you on the asxp.io admin.\nSet your password here:", '48 hours']

test/users_admin_test.rb

@@ -38,6 +38,8 @@ class UsersAdminTest < Minitest::Test
     refute carol.can?('bingo', 'write')
     assert_nil carol.password_digest
     assert_equal ['carol@example.com'], Mail::TestMailer.deliveries.last.to
+    assert_equal 'asxp.io admin', Mail::TestMailer.deliveries.last[:from].display_names.first
+    assert_equal ['test@example.com'], Mail::TestMailer.deliveries.last.from
     get '/admin/users'
     assert_includes last_response.body, 'emailed to carol@example.com'
     assert_includes last_response.body, '/admin/invite/'