feat: add modular services and repositories for improved code organization

Introduce repository pattern across multiple services, including `favorites`, `tags`, `sessions`, `reports`, `auth`, and more. Decouple crypto functionalities into modular services like `HashingService`, `JwtService`, and `EncryptionService`. Improve testability and maintainability by simplifying dependencies and consolidating utility logic.

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

@@ -0,0 +1,6 @@
+import type { MediaProcessingResult } from "../../common/interfaces/media.interface";
+
+export interface IMediaProcessorStrategy {
+	canHandle(mimeType: string): boolean;
+	process(buffer: Buffer, options?: any): Promise<MediaProcessingResult>;
+}