feat: redesign comments section for better UX/UI

- Redesigned comment cards with improved spacing and typography
- Added vertical line indicator for reply nesting
- Implemented native details/summary toggle for reply forms (replacing JS)
- Styled 'Join the conversation' section to be more distinct from existing comments
- Added solid-pink shadow to Tailwind configuration
- Updated E2E tests to match new UI structure and elements

theme/static_src/tailwind.config.js

@@ -28,6 +28,7 @@ module.exports = {
         'neon-pink': '0 0 20px rgba(236, 72, 153, 0.3)',
         'solid-dark': '6px 6px 0px 0px #09090b',
         'solid-light': '6px 6px 0px 0px #e4e4e7',
+        'solid-pink': '6px 6px 0px 0px #ec4899',
       },
     },
   },