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/effects.py

@@ -310,9 +310,11 @@ async def get_effect_source(
 @router.get("")
 async def list_effects(
     request: Request,
+    offset: int = 0,
+    limit: int = 20,
     ctx: UserContext = Depends(require_auth),
 ):
-    """List all uploaded effects."""
+    """List uploaded effects with pagination."""
     effects_dir = get_effects_dir()
     effects = []
 
@@ -341,18 +343,26 @@ async def list_effects(
     # Sort by upload time (newest first)
     effects.sort(key=lambda e: e.get("uploaded_at", ""), reverse=True)
 
+    # Apply pagination
+    total = len(effects)
+    paginated_effects = effects[offset:offset + limit]
+    has_more = offset + limit < total
+
     if wants_json(request):
-        return {"effects": effects}
+        return {"effects": paginated_effects, "offset": offset, "limit": limit, "has_more": has_more}
 
     from ..dependencies import get_nav_counts
     nav_counts = await get_nav_counts(ctx.actor_id)
 
     templates = get_templates(request)
     return render(templates, "effects/list.html", request,
-        effects=effects,
+        effects=paginated_effects,
         user=ctx,
         nav_counts=nav_counts,
         active_tab="effects",
+        offset=offset,
+        limit=limit,
+        has_more=has_more,
     )