fix: 首尾帧模式 aspect ratio 默认改为 adaptive（自适应）

切换到 keyframe 模式时自动设为 adaptive，API 根据首帧图片比例
自动匹配最接近的输出比例，避免图片与视频比例不匹配。
用户仍可手动选择固定比例覆盖。

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

web/src/components/Toolbar.tsx

@@ -88,6 +88,11 @@ const ratioItems = [
   { label: '9:16', value: '9:16' as AspectRatio },
 ];
 
+const keyframeRatioItems = [
+  { label: '自适应', value: 'adaptive' as AspectRatio },
+  ...ratioItems,
+];
+
 const durationItems = Array.from({ length: 12 }, (_, i) => {
   const v = i + 4;
   return { label: `${v}s`, value: String(v) };
@@ -175,25 +180,18 @@ export function Toolbar() {
       />
 
       {/* Aspect ratio */}
-      {isKeyframe ? (
-        <button className={styles.btn} style={{ opacity: 0.5, pointerEvents: 'none' }}>
-          <MonitorIcon />
-          <span className={styles.label}>自动匹配</span>
-        </button>
-      ) : (
-        <Dropdown
-          items={ratioItems}
-          value={aspectRatio}
-          onSelect={(v) => setAspectRatio(v as AspectRatio)}
-          minWidth={100}
-          trigger={
-            <button className={styles.btn}>
-              <MonitorIcon />
-              <span className={styles.label}>{aspectRatio}</span>
-            </button>
-          }
-        />
-      )}
+      <Dropdown
+        items={isKeyframe ? keyframeRatioItems : ratioItems}
+        value={aspectRatio}
+        onSelect={(v) => setAspectRatio(v as AspectRatio)}
+        minWidth={100}
+        trigger={
+          <button className={styles.btn}>
+            <MonitorIcon />
+            <span className={styles.label}>{aspectRatio === 'adaptive' ? '自适应' : aspectRatio}</span>
+          </button>
+        }
+      />
 
       {/* Duration */}
       <Dropdown

web/src/store/inputBar.ts

@@ -214,6 +214,7 @@ export const useInputBarStore = create<InputBarState>((set, get) => ({
         mode,
         prevReferences: state.references,
         references: [],
+        aspectRatio: 'adaptive',
         duration: 5,
       });
     } else {

web/src/types/index.ts

@@ -1,6 +1,6 @@
 export type CreationMode = 'universal' | 'keyframe';
 export type ModelOption = 'seedance_2.0' | 'seedance_2.0_fast';
-export type AspectRatio = '16:9' | '9:16' | '1:1' | '21:9' | '4:3' | '3:4';
+export type AspectRatio = '16:9' | '9:16' | '1:1' | '21:9' | '4:3' | '3:4' | 'adaptive';
 export type Duration = 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15;
 export type GenerationType = 'video' | 'image';
 export type UserRole = 'super_admin' | 'team_admin' | 'member';