Implements dynamic Open Graph (OG) metadata and image generation for
single-file shared boxes to improve social media previews.
Changes include:
- Added a new route `/d/{boxID}/f/{fileID}/og-image.jpg` for file-specific OG images.
- Updated `DownloadPage` to dynamically set the page title, description, and OG image properties when a box contains only one file.
- Restricted raw media inline serving for social bots to images and videos.
- Added helper functions to format file share descriptions and determine appropriate social image URLs and types.
- Integrated basic font rendering to support dynamic OG image generation.
Implement a rich file preview interface to allow users to view file
contents directly in the browser.
Changes include:
- Exposing raw file size (`SizeBytes`) in the download handler's file view.
- Adding comprehensive CSS styling for the preview layout and cards.
- Integrating Prism.js for syntax highlighting of code files.
- Updating Content Security Policy (CSP) headers to permit inline styles and frame sources required by the preview components.
- Adding unit tests to ensure preview metadata attributes are correctly rendered on the download page.
