Fix Buttondown form action URL

Use embed-subscribe endpoint for HTML form submission.

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

Author: dahlia

.claude/settings.local.json

@@ -24,3 +24,4 @@ dist-ssr
 *.sw?
 
 .playwright-mcp/
+.claude/settings.local.json

.gitignore

@@ -32,7 +32,7 @@
       <!-- Form -->
       <div class="max-w-md mx-auto">
         <form
-          action="https://buttondown.com/api/emails/fedify-studio"
+          action="https://buttondown.com/api/emails/embed-subscribe/fedify-studio"
           method="post"
           target="_blank"
           class="relative"