feat: Import video to Cap desktop, open in editor

[richiemcilroy]

This PR adds a video import flow to Cap Desktop.

New Video Importing Feature

• Introduce an importer module and register import_video_file in the async runtime (src-tauri/src/lib.rs)
• Add an “Importer” section under Settings with a new ImporterSettings component (routes/(window-chrome)/settings/importer.tsx)
• Expose importVideoFile helper in src/utils/tauri.ts to invoke the Tauri command

Demo:
https://cap.so/s/zd18xpcqgjfsx6x

[vipexv]

Any updates on this?