feat(content): serve the mounted content folder under /content (spec 003)

Audio with range requests, library.json, Homer books; LRC parser. Content
stays out of git and the image.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/server.ts

@@ -1,4 +1,5 @@
 import type { Server } from "bun";
+import { contentResponse } from "./content/routes";
 import home from "./index.html";
 import m0 from "./mockups/01-editorial/index.html";
 import m1 from "./mockups/02-vertical-story/index.html";
@@ -17,7 +18,13 @@ import m13 from "./mockups/14-voyage-panel/index.html";
 import m14 from "./mockups/15-voyage-look2/index.html";
 import m15 from "./mockups/16-voyage-readable/index.html";
 
-export function startServer(port: number): Server<undefined> {
+export interface ServerOptions {
+  /** Folder with the real content (audio, lyrics, Homer); defaults to CONTENT_DIR. See spec 003. */
+  contentDir?: string;
+}
+
+export function startServer(port: number, opts: ServerOptions = {}): Server<undefined> {
+  const contentDir = "contentDir" in opts ? opts.contentDir : process.env.CONTENT_DIR;
   return Bun.serve({
     port,
     routes: {
@@ -56,8 +63,8 @@ export function startServer(port: number): Server<undefined> {
       "/mockups/16-voyage-readable": Response.redirect("/mockups/16-voyage-readable/", 302),
     },
     development: process.env.NODE_ENV !== "production",
-    fetch() {
-      return new Response("Not found", { status: 404 });
+    fetch(req) {
+      return contentResponse(req, contentDir) ?? new Response("Not found", { status: 404 });
     },
   });
 }