feat(24-01): Add pricing to Gemini hardcoded models

Add pricing field to GEMINI_IMAGE_MODELS array:
- nano-banana: $0.039 per-run
- nano-banana-pro: $0.134 per-run

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

src/app/api/models/route.ts

@@ -55,6 +55,7 @@ const GEMINI_IMAGE_MODELS: ProviderModel[] = [
     provider: "gemini",
     capabilities: ["text-to-image", "image-to-image"],
     coverImage: undefined,
+    pricing: { type: "per-run", amount: 0.039, currency: "USD" },
   },
   {
     id: "nano-banana-pro",
@@ -63,6 +64,7 @@ const GEMINI_IMAGE_MODELS: ProviderModel[] = [
     provider: "gemini",
     capabilities: ["text-to-image", "image-to-image"],
     coverImage: undefined,
+    pricing: { type: "per-run", amount: 0.134, currency: "USD" },
   },
 ];