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/image-processor.strategy.ts

@@ -0,0 +1,44 @@
+import { BadRequestException, Injectable, Logger } from "@nestjs/common";
+import sharp from "sharp";
+import type { MediaProcessingResult } from "../../common/interfaces/media.interface";
+import type { IMediaProcessorStrategy } from "./media-processor.strategy";
+
+@Injectable()
+export class ImageProcessorStrategy implements IMediaProcessorStrategy {
+	private readonly logger = new Logger(ImageProcessorStrategy.name);
+
+	canHandle(mimeType: string): boolean {
+		return mimeType.startsWith("image/");
+	}
+
+	async process(
+		buffer: Buffer,
+		options: { format: "webp" | "avif" } = { format: "webp" },
+	): Promise<MediaProcessingResult> {
+		try {
+			const { format } = options;
+			let pipeline = sharp(buffer);
+			const metadata = await pipeline.metadata();
+
+			if (format === "webp") {
+				pipeline = pipeline.webp({ quality: 80, effort: 6 });
+			} else {
+				pipeline = pipeline.avif({ quality: 65, effort: 6 });
+			}
+
+			const processedBuffer = await pipeline.toBuffer();
+
+			return {
+				buffer: processedBuffer,
+				mimeType: `image/${format}`,
+				extension: format,
+				width: metadata.width,
+				height: metadata.height,
+				size: processedBuffer.length,
+			};
+		} catch (error) {
+			this.logger.error(`Error processing image: ${error.message}`);
+			throw new BadRequestException("Failed to process image");
+		}
+	}
+}