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>

docs/design/002-direction-round-notes.md

@@ -113,7 +113,8 @@ This file exists because of that request. It gets updated after every user messa
 2. Dispatch one agent per spike, at most 3 at a time. Point each at its report file and the brief, and tell it to continue from the checklist.
 3. Build 11.
 4. Rebuild the preview container from this branch:
-   `docker build -t epic-timeline . && docker rm -f epic-timeline-preview && docker run -d --restart unless-stopped -e PORT=3000 -p 10.20.20.2:8099:3000 --name epic-timeline-preview epic-timeline`
+   `docker build -t epic-timeline . && docker rm -f epic-timeline-preview && docker run -d --restart unless-stopped -e PORT=3000 -e CONTENT_DIR=/content -v /home/user/epic-the-musical-content:/content:ro -p 10.20.20.2:8099:3000 --name epic-timeline-preview epic-timeline`
+   (the content mount was added 2026-10-30, spec 003)
 5. Ask the user which chart approach reads best.
 
 ## 2026-10-29
@@ -304,6 +305,11 @@ What is in `~/epic-the-musical-content/` (1.5 GB, checked 2026-10-30):
   Docker image**; the server reads it from a `CONTENT_DIR` path, mounted read-only into the container.
   Needs the user's OK (it touches `src/server.ts`, the Dockerfile and the lyrics rule).
 
+- **User's answers (2026-10-30):** content access: **"Mount it, never commit"**; next step: **"Yes, in 17
+  after 16"** (16 finishes with its simulated player, then 17 uses real FLAC playback, line-synced
+  `.lrc` lyrics and the actual Odyssey passage). Implemented as spec `docs/specs/003-content-mount.md`.
+- Note: Butler's translation uses Roman names (Ulysses, Minerva, Jove). Worth a line in the UI.
+
 ## Open questions (in priority order)
 
 1. ~~Which sea-chart approach (08–11) reads best, or which mix?~~ 11's navigation + 10's style (§9).