feat: implement createNodeConnectedFromSource functionality for enhanced node creation

- Added a new mutation to create nodes connected to existing nodes, improving the canvas interaction model.
- Updated the CanvasPlacementContext to include createNodeConnectedFromSource, allowing for seamless node connections.
- Refactored the PromptNode component to utilize the new connection method, enhancing the workflow for AI image generation.
- Introduced optimistic updates for immediate UI feedback during node creation and connection processes.

components/canvas/nodes/base-node-wrapper.tsx

@@ -17,7 +17,8 @@ const RESIZE_CONFIGS: Record<string, ResizeConfig> = {
   group: { minWidth: 150, minHeight: 100 },
   image: { minWidth: 140, minHeight: 120, keepAspectRatio: true },
   asset: { minWidth: 140, minHeight: 208, keepAspectRatio: false },
-  "ai-image": { minWidth: 200, minHeight: 200 },
+  // Chrome 88 + min. Viewport 120 → äußere Mindesthöhe 208 (siehe canvas onNodesChange)
+  "ai-image": { minWidth: 200, minHeight: 208, keepAspectRatio: false },
   compare: { minWidth: 300, minHeight: 200 },
   prompt: { minWidth: 260, minHeight: 220 },
   text: { minWidth: 220, minHeight: 90 },