* feat: add deno install page
* feat: add deno install onboarding page
* feat: add ffmpeg, deno, brew install help page
* feat: improve on boarding page with deno install, setting, ffmpeg install
* refactor: update app configuration and onboarding flow
- Improved the onboarding page layout by adding a draggable region.
- Introduced a new writable store `appConfigLoaded` to track the loading status of app configuration.
- Updated the main application page to subscribe to `appConfigLoaded` for better handling of onboarding logic.
- Minor formatting changes in the ffmpeg installation help page for consistency.
