feat: 视频上传支持 (v0.11.7)

- 新增视频上传按钮，支持 mp4/avi/mov/mkv/webm (≤10MB)
- ffmpeg 1fps 提取帧序列，自动缩放至512px，带时序标注
- 消息中注入帧序列时间线，多模态模型原生理解视频时序
- 视频按钮与 vision 模型能力自动联动
- 版本号 0.11.6 → 0.11.7，同步更新 README/帮助面板/菜单

src/renderer/types.d.ts

@@ -271,6 +271,14 @@ export interface MetonaDesktopAPI {
     getStatuses: () => Promise<Array<{ name: string; running: boolean; toolCount: number }>>;
     refreshTools: (name: string) => Promise<Array<{ name: string; description?: string; inputSchema: Record<string, unknown> }>>;
   };
+  video: {
+    extractFrames: (filePath: string, options?: { maxFrames?: number; maxWidth?: number; maxSize?: number }) => Promise<{
+      success: boolean;
+      frames?: Array<{ name: string; base64: string; timestampSeconds: number }>;
+      videoInfo?: { duration: number; width: number; height: number };
+      error?: string;
+    }>;
+  };
 }
 
 export interface AppInfo {