Add pagination and API improvements

- Add pagination to effects list with infinite scroll
- Refactor home stats into reusable get_user_stats function
- Add /api/stats endpoint for CLI/API clients
- Add has_more flag to recipes listing
- Add JSON API support to storage type page

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/routers/storage.py

@@ -271,6 +271,8 @@ async def storage_type_page(
     ctx = auth_service.get_user_from_cookie(request)
 
     if not ctx:
+        if wants_json(request):
+            raise HTTPException(401, "Authentication required")
         return RedirectResponse(url="/auth", status_code=302)
 
     if provider_type not in STORAGE_PROVIDERS_INFO:
@@ -279,6 +281,13 @@ async def storage_type_page(
     storages = await storage_service.list_by_type(ctx.actor_id, provider_type)
     provider_info = STORAGE_PROVIDERS_INFO[provider_type]
 
+    if wants_json(request):
+        return {
+            "provider_type": provider_type,
+            "provider_info": provider_info,
+            "storages": storages,
+        }
+
     from ..dependencies import get_nav_counts
     nav_counts = await get_nav_counts(ctx.actor_id)