feat: add nano-banana-2 pricing to cost calculator

Add per-resolution pricing for nano-banana-2 (512/1K/2K/4K).
Add 512px tier to all model pricing tables.
Use MODEL_DISPLAY_NAMES lookup instead of ternaries.
Add getPricing fallback for nano-banana-2 / gemini-3.1-flash-image-preview.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/utils/costCalculator.ts

@@ -1,25 +1,33 @@
-import { ModelType, Resolution, NanoBananaNodeData, GenerateVideoNodeData, Generate3DNodeData, SplitGridNodeData, WorkflowNode, ProviderType } from "@/types";
+import { ModelType, Resolution, MODEL_DISPLAY_NAMES, NanoBananaNodeData, GenerateVideoNodeData, Generate3DNodeData, SplitGridNodeData, WorkflowNode, ProviderType } from "@/types";
 
 // Pricing in USD per image (Gemini API)
 export const PRICING = {
   "nano-banana": {
+    "512": 0.039,
     "1K": 0.039,
     "2K": 0.039, // nano-banana only supports 1K
     "4K": 0.039,
   },
   "nano-banana-pro": {
+    "512": 0.134,
     "1K": 0.134,
     "2K": 0.134,
     "4K": 0.24,
   },
+  "nano-banana-2": {
+    "512": 0.045,
+    "1K": 0.067,
+    "2K": 0.101,
+    "4K": 0.151,
+  },
 } as const;
 
 export function calculateGenerationCost(model: ModelType, resolution: Resolution): number {
-  // nano-banana only supports 1K resolution
+  // nano-banana only supports 1K resolution (flat pricing)
   if (model === "nano-banana") {
     return PRICING["nano-banana"]["1K"];
   }
-  return PRICING["nano-banana-pro"][resolution];
+  return PRICING[model][resolution];
 }
 
 /**
@@ -153,6 +161,10 @@ export function calculatePredictedCost(
         const res = resolution || "1K";
         return { unitCost: PRICING["nano-banana-pro"][res], unit: "image" };
       }
+      if (modelId === "nano-banana-2" || modelId === "gemini-3.1-flash-image-preview") {
+        const res = resolution || "1K";
+        return { unitCost: PRICING["nano-banana-2"][res], unit: "image" };
+      }
     }
 
     // No pricing available (e.g., Replicate)
@@ -178,7 +190,7 @@ export function calculatePredictedCost(
         // Legacy Gemini-only model
         provider = "gemini";
         modelId = data.model;
-        modelName = data.model === "nano-banana" ? "Nano Banana" : "Nano Banana Pro";
+        modelName = MODEL_DISPLAY_NAMES[data.model] || data.model;
       }
 
       const resolution = data.model === "nano-banana" ? "1K" : data.resolution;
@@ -215,7 +227,7 @@ export function calculatePredictedCost(
       if (data.isConfigured && data.targetCount > 0) {
         const model = data.generateSettings.model;
         const resolution = model === "nano-banana" ? "1K" : data.generateSettings.resolution;
-        const modelName = model === "nano-banana" ? "Nano Banana" : "Nano Banana Pro";
+        const modelName = MODEL_DISPLAY_NAMES[model] || model;
 
         const pricing = getPricing("gemini", model, resolution);
         const unitCost = pricing?.unitCost ?? null;