feat: add video upload feature with support for validation and processing

- Introduced "video" as a new content type across backend and frontend.
- Updated validation schemas and MIME-type handling for video files.
- Implemented file size limits for videos (10 MB max) in configuration.
- Enhanced upload flow with auto-detection of file types (image, GIF, video).
- Expanded media processing to handle video files and convert them to WebM format.

backend/src/media/strategies/video-processor.strategy.ts

@@ -12,7 +12,7 @@ export class VideoProcessorStrategy implements IMediaProcessorStrategy {
 	private readonly logger = new Logger(VideoProcessorStrategy.name);
 
 	canHandle(mimeType: string): boolean {
-		return mimeType.startsWith("video/");
+		return mimeType.startsWith("video/") || mimeType === "image/gif";
 	}
 
 	async process(