Add collections pagination and a search field on the search page

Paginate the collections grid with a "See more" button backed by a new
getCollectionsPage cursor API, add an editable search input to the
search-results block, and bump @shopify/hydrogen to 2026.10.0-preview.1.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DqFkSaLYRPZ18dsMbzjiP4

app/search/page.json

@@ -18,7 +18,8 @@
       "type": "search-results",
       "props": {
         "id": "search-results",
-        "title": "Search"
+        "title": "Search",
+        "placeholder": "Search products"
       }
     },
     {