Docker image: enable non-free for fdkaac's library

CLAUDE.md

@@ -133,7 +133,7 @@ JSON shapes mirror the Tauri Rust bridge exactly — don't change one side alone
   send `?still=1` → the device stores `<id>.m4a` + OPFS `art/<id>.jpg` and plays it as
   audio with the picture; online, still songs also play audio + `/api/media/:id/art`.
 - **Compact audio (HE-AAC)**: `<id>.<gen>.he.m4a`, ~48 kbps HE-AAC v1 from **fdkaac**
-  (Debian contrib — ffmpeg's encoder is LC only), one niced lane, made for every copy and
+  (Debian contrib + non-free — ffmpeg's encoder is LC only), one niced lane, made for every copy and
   moved to the front when a device asks (`prepare?audio=he` → `working` until ready).
   Columns `he_size` (NULL = not made, 0 = failed/not smaller) + `he_sha256`. Devices ask
   for it with Settings → "Save songs as compact audio" or Saved videos → Shrink

Dockerfile

@@ -16,9 +16,10 @@ FROM oven/bun:1-debian
 # ca-certificates for HTTPS fetches from yt-dlp
 # ffmpeg lets yt-dlp merge bestvideo+bestaudio into a single mp4 for the
 # "Save before playing" download path (GET /api/download?mux=1)
-# fdkaac (Debian contrib) encodes the compact HE-AAC audio phones can save;
+# fdkaac (Debian contrib; its libfdk-aac2t64 is non-free) encodes the compact
+# HE-AAC audio phones can save;
 # ffmpeg's built-in AAC encoder only does AAC-LC.
-RUN sed -i 's/^Components: main$/Components: main contrib/' /etc/apt/sources.list.d/debian.sources && \
+RUN sed -i 's/^Components: main$/Components: main contrib non-free/' /etc/apt/sources.list.d/debian.sources && \
     apt-get update -qq && \
     apt-get install -y --no-install-recommends \
       curl \