feat(17-01): add S3 storage service with upload, delete, and presigned URL support

- Create storage.service.ts wrapping @aws-sdk/client-s3 with forcePathStyle for MinIO
- Export uploadImage, deleteImage, getImageUrl, withImageUrl, withImageUrls
- Add unit tests with mocked S3Client (8 tests passing)
- Install @aws-sdk/client-s3 and @aws-sdk/s3-request-presigner

src/server/services/storage.service.ts

@@ -0,0 +1,83 @@
+import {
+	DeleteObjectCommand,
+	GetObjectCommand,
+	PutObjectCommand,
+	S3Client,
+} from "@aws-sdk/client-s3";
+import { getSignedUrl } from "@aws-sdk/s3-request-presigner";
+
+// MinIO GitHub repository was archived Feb 2026. The S3 API abstraction
+// makes the underlying provider swappable (SeaweedFS, Garage, AWS S3, etc.)
+// without code changes.
+
+const s3 = new S3Client({
+	endpoint: process.env.S3_ENDPOINT,
+	region: process.env.S3_REGION ?? "us-east-1",
+	credentials: {
+		accessKeyId: process.env.S3_ACCESS_KEY!,
+		secretAccessKey: process.env.S3_SECRET_KEY!,
+	},
+	forcePathStyle: true, // REQUIRED for MinIO and most S3-compatible services
+});
+
+const bucket = process.env.S3_BUCKET ?? "gearbox-images";
+const presignExpiry = Number.parseInt(
+	process.env.S3_PRESIGN_EXPIRY ?? "3600",
+	10,
+);
+
+export async function uploadImage(
+	buffer: Buffer | ArrayBuffer,
+	filename: string,
+	contentType: string,
+): Promise<void> {
+	await s3.send(
+		new PutObjectCommand({
+			Bucket: bucket,
+			Key: filename,
+			Body: Buffer.from(buffer),
+			ContentType: contentType,
+		}),
+	);
+}
+
+export async function deleteImage(filename: string): Promise<void> {
+	await s3.send(
+		new DeleteObjectCommand({
+			Bucket: bucket,
+			Key: filename,
+		}),
+	);
+}
+
+export async function getImageUrl(filename: string): Promise<string> {
+	const command = new GetObjectCommand({
+		Bucket: bucket,
+		Key: filename,
+	});
+	return getSignedUrl(s3, command, { expiresIn: presignExpiry });
+}
+
+/**
+ * Enrich a record that has an imageFilename with a presigned imageUrl.
+ * Returns null imageUrl when imageFilename is null.
+ */
+export async function withImageUrl<
+	T extends { imageFilename: string | null },
+>(record: T): Promise<T & { imageUrl: string | null }> {
+	return {
+		...record,
+		imageUrl: record.imageFilename
+			? await getImageUrl(record.imageFilename)
+			: null,
+	};
+}
+
+/**
+ * Batch version of withImageUrl. Uses Promise.all for parallelism.
+ */
+export async function withImageUrls<
+	T extends { imageFilename: string | null },
+>(records: T[]): Promise<(T & { imageUrl: string | null })[]> {
+	return Promise.all(records.map((record) => withImageUrl(record)));
+}