feat: enhance AI image generation and prompt handling in canvas components

- Introduced shimmer animation for loading states in AI image nodes.
- Updated prompt node to handle image generation with improved error handling and user feedback.
- Refactored AI image node to manage generation status and display loading indicators.
- Enhanced data handling in canvas components to include canvasId for better context management.
- Improved status message handling in Convex mutations for clearer user feedback.

lib/ai-models.ts

@@ -0,0 +1,45 @@
+// Client-side model definitions for the UI.
+// Mirrors the backend config in convex/openrouter.ts — keep in sync.
+
+export interface AiModel {
+  id: string;
+  name: string;
+  tier: "budget" | "standard" | "premium";
+  description: string;
+  estimatedCost: string; // human-readable, e.g. "~€0.04"
+  minTier: "free" | "starter" | "pro" | "business"; // minimum subscription tier
+}
+
+export const IMAGE_MODELS: AiModel[] = [
+  {
+    id: "google/gemini-2.5-flash-image",
+    name: "Gemini 2.5 Flash",
+    tier: "standard",
+    description: "Fast, high-quality generation",
+    estimatedCost: "~€0.04",
+    minTier: "free",
+  },
+  // Phase 2 — uncomment when model selector UI is ready:
+  // {
+  //   id: "black-forest-labs/flux.2-klein-4b",
+  //   name: "FLUX.2 Klein",
+  //   tier: "budget",
+  //   description: "Photorealism, fastest Flux",
+  //   estimatedCost: "~€0.02",
+  //   minTier: "free",
+  // },
+  // {
+  //   id: "openai/gpt-5-image",
+  //   name: "GPT-5 Image",
+  //   tier: "premium",
+  //   description: "Best instruction following, text in image",
+  //   estimatedCost: "~€0.15",
+  //   minTier: "starter",
+  // },
+];
+
+export const DEFAULT_MODEL_ID = "google/gemini-2.5-flash-image";
+
+export function getModel(id: string): AiModel | undefined {
+  return IMAGE_MODELS.find((m) => m.id === id);
+}