Fix button roundtrip in editor, alignment persistence, and test email rendering

admin-spa/src/components/ui/rich-text-editor.tsx

@@ -50,6 +50,8 @@ export function RichTextEditor({
       Placeholder.configure({
         placeholder,
       }),
+      // ButtonExtension MUST come before Link to ensure buttons are parsed first
+      ButtonExtension,
       Link.configure({
         openOnClick: false,
         HTMLAttributes: {
@@ -65,7 +67,6 @@ export function RichTextEditor({
           class: 'max-w-full h-auto rounded',
         },
       }),
-      ButtonExtension,
     ],
     content,
     onUpdate: ({ editor }) => {