feat: add Nano Banana 2 model, revert default to Nano Banana Pro, bump v0.16.0

模型变更:
- 新增 Nano Banana 2 (gemini-3.1-flash-image-preview) 到模型列表
- 默认模型恢复为 Nano Banana Pro (gemini-3-pro-image-preview)
  原因：Nano Banana 2 刚发布，部分区域尚未完全上线，调用会超时
- 模型列表顺序：Nano Banana 2 > Nano Banana Pro > Nano Banana
- 更新 ProviderManager、image-generator.ts、media/generate route 的默认值

依赖更新:
- @ai-sdk/google 3.0.31 → 3.0.32

版本:
- package.json 版本号 0.15.1 → 0.16.0

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

Author: 7418

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "codepilot",
-  "version": "0.15.1",
+  "version": "0.16.0",
   "private": true,
   "author": {
     "name": "op7418",

package.json

@@ -41,7 +41,7 @@ export async function POST(request: NextRequest) {
         id: result.mediaGenerationId,
         text: '',
         images: result.images,
-        model: body.model || 'gemini-3.1-flash-image-preview',
+        model: body.model || 'gemini-3-pro-image-preview',
         imageSize: body.imageSize || '1K',
         elapsedMs: result.elapsedMs,
       }),

src/app/api/media/generate/route.ts

@@ -247,8 +247,8 @@ const QUICK_PRESETS: QuickPreset[] = [
   {
     key: "gemini-image",
     name: "Google Gemini (Image)",
-    description: "Nano Banana 2 — AI image generation by Google Gemini",
-    descriptionZh: "Nano Banana 2 — Google Gemini AI 图片生成",
+    description: "Nano Banana Pro — AI image generation by Google Gemini",
+    descriptionZh: "Nano Banana Pro — Google Gemini AI 图片生成",
     icon: <Google size={18} />,
     provider_type: "gemini-image",
     base_url: "https://generativelanguage.googleapis.com/v1beta",
@@ -264,7 +264,7 @@ const GEMINI_IMAGE_MODELS = [
   { value: 'gemini-2.5-flash-image', label: 'Nano Banana' },
 ];
 
-const DEFAULT_GEMINI_IMAGE_MODEL = 'gemini-3.1-flash-image-preview';
+const DEFAULT_GEMINI_IMAGE_MODEL = 'gemini-3-pro-image-preview';
 
 function getGeminiImageModel(provider: ApiProvider): string {
   try {

src/components/settings/ProviderManager.tsx

@@ -43,7 +43,7 @@ export async function generateSingleImage(params: GenerateSingleImageParams): Pr
   }
 
   // Read configured model from extra_env, fall back to default
-  let configuredModel = 'gemini-3.1-flash-image-preview';
+  let configuredModel = 'gemini-3-pro-image-preview';
   try {
     const env = JSON.parse(provider.extra_env || '{}');
     if (env.GEMINI_IMAGE_MODEL) configuredModel = env.GEMINI_IMAGE_MODEL;