feat: 接入 Seedance 视频节点并增强图像节点功能

- 新增 Seedance 文生视频、图生视频、首尾帧生视频三个节点
- 新增 seedance_client.py 客户端
- 为 NanoBananaPro、BatchNanoBananaPro、全能生图节点添加「跳过错误」开关，出错时返回占位图以继续队列
- 修复 nano-banana-2-限时特价 动态端点路由（按分辨率选择）
- 统一分辨率选项命名：512 → 512px

Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

clients/gemini_client.py

@@ -62,8 +62,20 @@ class GeminiAPIClient(BaseAPIClient):
             else:
                 return "/v1beta/models/nano-banana-pro-2k:generateContent"
 
+        elif model == "nano-banana-2-限时特价":
+            if resolution == "512px":
+                return "/v1beta/models/nano-banana-2-0.5k:generateContent"
+            elif resolution == "1K":
+                return "/v1beta/models/nano-banana-2-1k:generateContent"
+            elif resolution == "2K":
+                return "/v1beta/models/nano-banana-2-2k:generateContent"
+            elif resolution == "4K":
+                return "/v1beta/models/nano-banana-2-4k:generateContent"
+            else:
+                return "/v1beta/models/nano-banana-2-2k:generateContent"
+
         elif model == "nano-banana-2-官方计费":
-            if resolution == "512":
+            if resolution == "512px":
                 return "/v1beta/models/nano-banana-2-0.5k-official:generateContent"
             elif resolution == "1K":
                 return "/v1beta/models/nano-banana-2-1k-official:generateContent"