Harden auth, payments, and frontend against review findings.

Close exploitable gaps in booking/payment flows, enforce token versioning and account checks, gate sensitive payment data, and add middleware plus input validation across admin routes.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/ui/RichTextEditor.tsx

@@ -14,11 +14,18 @@ interface RichTextEditorProps {
   editable?: boolean;
 }
 
+// Escape HTML-significant characters so any raw HTML embedded in the markdown source
+// is neutralised before we layer our own generated tags on top (defense-in-depth;
+// the public renderer escapes too, and TipTap sanitizes via its schema).
+function escapeRawHtml(s: string): string {
+  return s.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
+}
+
 // Convert markdown to HTML for TipTap
 function markdownToHtml(markdown: string): string {
   if (!markdown) return '<p></p>';
   
-  let html = markdown;
+  let html = escapeRawHtml(markdown);
   
   // Convert horizontal rules first (before other processing)
   html = html.replace(/^---+$/gm, '<hr>');