feat: add MediaModule with service for virus scanning and media processing

Introduced MediaModule with MediaService to handle antivirus scanning using ClamAV and media file processing for images (webp/avif) and videos (webm/av1). Includes media-related interfaces and module exports for broader application integration.

backend/src/media/interfaces/media.interface.ts

@@ -0,0 +1,13 @@
+export interface MediaProcessingResult {
+	buffer: Buffer;
+	mimeType: string;
+	extension: string;
+	width?: number;
+	height?: number;
+	size: number;
+}
+
+export interface ScanResult {
+	isInfected: boolean;
+	virusName?: string;
+}