feat: enhance dashboard and canvas components with credit management features

- Integrated CreditOverview and RecentTransactions components into the dashboard for better credit visibility.
- Updated canvas toolbar to display current credit balance using CreditDisplay.
- Improved AI image and prompt nodes to show credit costs and handle credit availability checks during image generation.
- Added new queries for fetching recent transactions and monthly usage statistics to support dashboard features.
- Refactored existing code to streamline credit-related functionalities across components.

components/canvas/canvas-toolbar.tsx

@@ -2,6 +2,7 @@
 
 import { useRef } from "react";
 
+import { CreditDisplay } from "@/components/canvas/credit-display";
 import { ExportButton } from "@/components/canvas/export-button";
 import { useCanvasPlacement } from "@/components/canvas/canvas-placement-context";
 
@@ -98,6 +99,7 @@ export default function CanvasToolbar({
         </button>
       ))}
       <div className="ml-1 h-6 w-px bg-border" />
+      <CreditDisplay />
       <ExportButton canvasName={canvasName ?? "canvas"} />
     </div>
   );