fix email settings: missing providers, a11y, no-JS support

show all 10 providers in three groups (popular, transactional,
advanced) with category headings. fix phx-change clobbering text
fields, async test email sending state, integer parse crash on
bad port. add keyboard focus on card radios, fieldset legend,
WCAG-compliant badge contrast, responsive grid. extract shared
save_config into Mailer, add no-JS controller fallback with
configured_adapter hidden field for adapter change detection.
remove CardRadioScroll JS hook (no longer needed).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/berrypod_web/router.ex

@@ -138,6 +138,10 @@ defmodule BerrypodWeb.Router do
     get "/analytics/export", AnalyticsExportController, :export
     get "/newsletter/export", NewsletterExportController, :export
 
+    # No-JS fallbacks for email settings
+    post "/settings/email", EmailSettingsController, :update
+    post "/settings/email/test", EmailSettingsController, :test
+
     live_session :admin,
       layout: {BerrypodWeb.Layouts, :admin},
       on_mount: [