Fix model constants per PR review

- Remove video models (t2v/i2v/videoedit/r2v) from ImageGeneration
- Remove WAN2_6_* from VideoSynthesis (WAN_2_7_* supersedes)
- Remove WanX2_6_IMAGE from ImageGeneration (WanX2_7_IMAGE supersedes)
- Use WAN_ prefix for new video synthesis constants instead of WAN2_

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: zhansheng.lzs

src/main/java/com/alibaba/dashscope/aigc/imagegeneration/ImageGeneration.java

@@ -36,14 +36,9 @@ public final class ImageGeneration {
 
   public static class Models {
     public static final String WanX2_6_T2I = "wan2.6-t2i";
-    public static final String WanX2_6_IMAGE = "wan2.6-image";
 
-    public static final String WanX2_7_T2V = "wan2.7-t2v";
-    public static final String WanX2_7_I2V = "wan2.7-i2v";
     public static final String WanX2_7_IMAGE = "wan2.7-image";
     public static final String WanX2_7_IMAGE_PRO = "wan2.7-image-pro";
-    public static final String WanX2_7_VIDEOEDIT = "wan2.7-videoedit";
-    public static final String WanX2_7_R2V = "wan2.7-r2v";
 
     public static final String QWEN_IMAGE = "qwen-image";
     public static final String QWEN_IMAGE_EDIT = "qwen-image-edit";

src/main/java/com/alibaba/dashscope/aigc/videosynthesis/VideoSynthesis.java

@@ -39,14 +39,10 @@ public static class Models {
     public static final String WANX_2_1_KF2V_PLUS = "wanx2.1-kf2v-plus";
     public static final String WANX_KF2V = "wanx-kf2v";
 
-    public static final String WAN2_6_T2V = "wan2.6-t2v";
-    public static final String WAN2_6_I2V = "wan2.6-i2v";
-    public static final String WAN2_6_R2V = "wan2.6-r2v";
-
-    public static final String WAN2_7_T2V = "wan2.7-t2v";
-    public static final String WAN2_7_I2V = "wan2.7-i2v";
-    public static final String WAN2_7_R2V = "wan2.7-r2v";
-    public static final String WAN2_7_VIDEOEDIT = "wan2.7-videoedit";
+    public static final String WAN_2_7_T2V = "wan2.7-t2v";
+    public static final String WAN_2_7_I2V = "wan2.7-i2v";
+    public static final String WAN_2_7_R2V = "wan2.7-r2v";
+    public static final String WAN_2_7_VIDEOEDIT = "wan2.7-videoedit";
 
     public static final String HAPPYHORSE_1_0_T2V = "happyhorse-1.0-t2v";
     public static final String HAPPYHORSE_1_0_I2V = "happyhorse-1.0-i2v";