feat(image): 支持真 16:9(1536x864)+ 人物/商品三视图/场景默认 16:9

- gpt-image-2 实测支持 16:9(宽高需被 16 整除):真 16:9 = 1536x864(长边封顶 1536);
  原来「16:9」误给成 1536x1024(实为 3:2)。修正 _RATIO_TO_SIZE 与 _ratio_to_image_size
- admin「提示词」页比例按钮新增「宽 16:9」
- 迁移 0015/0016:scene + product_triview + person_triview 默认比例设为 16:9;
  分镜图(storyboard_frame)/立绘/视频保持竖屏不动

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/backend/apps/ai/migrations/0015_scene_product_16_9.py

@@ -0,0 +1,19 @@
+from django.db import migrations
+
+# 场景 / 商品三视图 默认比例改 16:9(1536x864);分镜图(storyboard_frame)保持竖屏不动。
+KEYS = ["scene", "product_triview"]
+
+
+def forwards(apps, schema_editor):
+    apps.get_model("ai", "PromptTemplate").objects.filter(key__in=KEYS).update(ratio="16:9")
+
+
+def backwards(apps, schema_editor):
+    apps.get_model("ai", "PromptTemplate").objects.filter(key__in=KEYS).update(ratio="landscape")
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("ai", "0014_video_prompt_dialogue_no_meta")]
+
+    operations = [migrations.RunPython(forwards, backwards)]

core/backend/apps/ai/migrations/0016_person_triview_16_9.py

@@ -0,0 +1,18 @@
+from django.db import migrations
+
+# 人物三视图 也改 16:9(1536x864)。0015 已处理场景/商品三视图,这里补人物三视图。
+
+
+def forwards(apps, schema_editor):
+    apps.get_model("ai", "PromptTemplate").objects.filter(key="person_triview").update(ratio="16:9")
+
+
+def backwards(apps, schema_editor):
+    apps.get_model("ai", "PromptTemplate").objects.filter(key="person_triview").update(ratio="landscape")
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("ai", "0015_scene_product_16_9")]
+
+    operations = [migrations.RunPython(forwards, backwards)]

core/backend/apps/ai/services.py

@@ -723,13 +723,13 @@ def _find_entity_group(project, kind: str, label: str, group_id: str | None):
 
 
 def _ratio_to_image_size(ratio: str) -> str:
-    """前端比例(1:1 / 3:4 / 9:16)→ gpt-image 支持的尺寸。竖屏统一 1024x1536,横屏 1536x1024。"""
+    """前端比例 → gpt-image 支持的尺寸(宽高均需被 16 整除)。16:9 用真 16:9 的 1536x864,4:3 用 1536x1024。"""
     return {
         "1:1": "1024x1024",
         "3:4": "1024x1536",
         "9:16": "1024x1536",
         "4:3": "1536x1024",
-        "16:9": "1536x1024",
+        "16:9": "1536x864",  # 真 16:9(原来误用 1536x1024 = 3:2)
     }.get((ratio or "").strip(), "1024x1024")
 
 
@@ -768,7 +768,8 @@ def quality_suffix(stage: str, fallback: str, slot: str = "quality", sep: str =
 
 
 _PROMPT_PLACEHOLDER_RE = re.compile(r"\{(\w+)\}", re.UNICODE)
-_RATIO_TO_SIZE = {"1:1": "1024x1024", "portrait": "1024x1536", "landscape": "1536x1024"}
+# gpt-image 要求宽高都能被 16 整除;1536x864 = 真 16:9(长边封顶 1536),1536x1024 = 3:2
+_RATIO_TO_SIZE = {"1:1": "1024x1024", "portrait": "1024x1536", "landscape": "1536x1024", "16:9": "1536x864"}
 
 
 def _prompt_template_row(key: str):

core/frontend/src/routes/admin/admin-prompts.tsx

@@ -10,7 +10,8 @@ const RATIOS = [
   { key: "", label: "默认" },
   { key: "1:1", label: "1:1 方" },
   { key: "portrait", label: "竖 2:3" },
-  { key: "landscape", label: "横 3:2" }
+  { key: "landscape", label: "横 3:2" },
+  { key: "16:9", label: "宽 16:9" }
 ];
 
 export function AdminPromptsPage({ notify }: { notify: Notify }) {