### Description
Explore Feed has multiple Liquid Glass violations:
- iPhone: abrupt gray tab bar background, low contrast search
- iPad: missing logo, incorrect search treatment
Explore Feed is the primary discovery surface and often the first screen users see.
### Requirements
iPhone
[] Improve search contrast
[] Secondary color for overflow menu
[] Toolbar fixed on scroll (Apple News-like)
[] [[ https://www.figma.com/design/nXIizaWUKh7yuS52LrTkch/Liquid-Glass-Redesign-version?node-id=6169-27466&t=SjmVpd6yIYdjmB35-4 | Hide top nav on scroll down ]], show it again [[ https://www.figma.com/design/nXIizaWUKh7yuS52LrTkch/Liquid-Glass-Redesign-version?node-id=6169-27467&t=SjmVpd6yIYdjmB35-4 | on scroll up. ]]
iPad
[] Add logo top-left
[] Search icon
[] Fixed toolbar on scroll
] [[ https://www.figma.com/design/nXIizaWUKh7yuS52LrTkch/Liquid-Glass-Redesign-version?node-id=6169-29325&t=SjmVpd6yIYdjmB35-4 | Hide top nav on scroll down ]], show it again [[ https://www.figma.com/design/nXIizaWUKh7yuS52LrTkch/Liquid-Glass-Redesign-version?node-id=6171-25675&t=SjmVpd6yIYdjmB35-4 | on scroll up. ]]
#### Acceptance Criteria
- Search and toolbar match iOS 26 patterns
- Contrast meets accessibility standards
- Layout matches Figma
### Design References
iPhone: https://www.figma.com/design/nXIizaWUKh7yuS52LrTkch/Liquid-Glass-Redesign-version?node-id=5954-8144
iPad: https://www.figma.com/design/nXIizaWUKh7yuS52LrTkch/Liquid-Glass-Redesign-version?node-id=5909-3349
### Platforms
[X] iPhone
[X] iPad