Category responsive + but scrollable

### 🐛 Describe the bug

The CategoryScreen has two main UI issues affecting usability and responsiveness:
🔴 1. ListView is not scrollable (Critical)

The ListView.builder is configured with:

NeverScrollableScrollPhysics()
shrinkWrap: true
primary: true

This combination disables user scrolling and prevents the list from behaving as a proper scrollable widget.

Impact:
Users cannot scroll through stories when the list is long
Breaks expected app behavior
Causes poor user experience
🟠 2. Empty state layout is not responsive (Major)

The empty-state UI uses a fixed bottom padding:

EdgeInsets.only(bottom: 150.0)

This hard-coded value does not adapt to different screen sizes.

Impact:
UI appears misaligned on smaller or larger devices
Poor responsiveness across devices
Not following Flutter layout best practices
Expected Behavior
The stories list should scroll normally when content exceeds screen height
The empty state should be vertically centered and responsive on all screen sizes
Current Behavior
List does not scroll
Empty state positioning is inconsistent depending on device size
Suggested Fix
Remove NeverScrollableScrollPhysics, shrinkWrap, and primary from ListView
Replace fixed bottom padding with a responsive layout using Center, SafeArea, or flexible widgets
Environment
Flutter (mobile)
Affects CategoryScreen