Implement lazy loading in Explore Search, Buy & Sell, and Feed

Explore Search, Buy & Sell, and Feed currently load all posts/results at once in a single API call. On large datasets this causes slow initial load times, high memory usage, and a poor user experience. These should be converted to lazy-load (paginated) lists that fetch the next page as the user scrolls toward the bottom.

Expected behavior:
Initial load fetches only the first page (e.g. 20 items)
As user scrolls near the bottom, the next page is automatically fetched and appended
A loading spinner is shown at the bottom while fetching
When all pages are exhausted, show an "end of list" indicator
Pull to refresh resets to page 1

Blogs already implements lazy loading take help from there