[FIX] website_sale_aplicoop: Complete infinite scroll and search filter integration

Major fixes:
- Fix JSON body parsing in load_products_ajax with type='http' route
  * Parse JSON from request.httprequest.get_data() instead of post params
  * Correctly read page, search, category from JSON request body

- Fix search and category filter combination
  * Use intersection (&) instead of replacement to preserve both filters
  * Now respects search AND category simultaneously

- Integrate realtime_search.js with infinite_scroll.js
  * Add resetWithFilters() method to reset scroll to page 1 with new filters
  * When search/category changes, reload products from server
  * Clear grid and load fresh results

- Fix pagination reset logic
  * Set currentPage = 0 in resetWithFilters() so loadNextPage() increments to 1
  * Prevents loading empty page 2 when resetting filters

Results:
✅ Infinite scroll loads all pages correctly (1, 2, 3...)
✅ Search filters work across all products (not just loaded)
✅ Category filters work correctly
✅ Search AND category filters work together
✅ Page resets to 1 when filters change

website_sale_aplicoop/__manifest__.py

@@ -48,6 +48,7 @@
     "assets": {
         "web.assets_frontend": [
             "website_sale_aplicoop/static/src/css/website_sale.css",
+            "website_sale_aplicoop/static/src/js/infinite_scroll.js",
         ],
         "web.assets_tests": [
             "website_sale_aplicoop/static/tests/test_suite.js",