feat(media): add reference-aware S3 image delivery

lib/media/storage.ts

@@ -0,0 +1,25 @@
+import "server-only";
+
+import { S3Client } from "bun";
+
+let client: S3Client | undefined;
+
+function required(name: string): string {
+  const value = process.env[name];
+  if (!value) throw new Error(`${name} is required for media storage.`);
+  return value;
+}
+
+export function getMediaStorage(): S3Client {
+  if (!client) {
+    client = new S3Client({
+      accessKeyId: required("S3_ACCESS_KEY_ID"),
+      secretAccessKey: required("S3_SECRET_ACCESS_KEY"),
+      bucket: required("S3_BUCKET"),
+      endpoint: required("S3_ENDPOINT"),
+      region: process.env.S3_REGION || "auto",
+      virtualHostedStyle: process.env.S3_VIRTUAL_HOSTED_STYLE === "true",
+    });
+  }
+  return client;
+}