add streaming and mobile-app instructions

stream-relay/Dockerfile

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+FROM alpine:3.20
+
+RUN apk add --no-cache ffmpeg
+
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+
+ENTRYPOINT ["/entrypoint.sh"]

stream-relay/entrypoint.sh

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+#!/bin/sh
+set -e
+
+FIFO=/audio/stream.fifo
+ICECAST_HOST=${ICECAST_HOST:-icecast}
+ICECAST_PORT=${ICECAST_PORT:-8000}
+ICECAST_PASSWORD=${ICECAST_SOURCE_PASSWORD:-groove_source}
+MOUNT=${ICECAST_MOUNT:-/stream.flac}
+
+until [ -p "$FIFO" ]; do
+    echo "[stream-relay] Waiting for $FIFO..."
+    sleep 2
+done
+
+# Open FIFO with O_RDWR so Mopidy's GStreamer filesink never blocks on open().
+# A write-only open blocks until a reader exists; by holding the FIFO open
+# O_RDWR here, the write side can proceed immediately at any time.
+exec 5<>"$FIFO"
+
+echo "[stream-relay] FIFO open. Encoding PCM → FLAC → icecast://${ICECAST_HOST}:${ICECAST_PORT}${MOUNT}"
+
+ICECAST_URL="icecast://source:${ICECAST_PASSWORD}@${ICECAST_HOST}:${ICECAST_PORT}${MOUNT}"
+
+while true; do
+    ffmpeg -nostdin \
+        -f s16le -ar 48000 -ac 2 \
+        -i "$FIFO" \
+        -vn \
+        -c:a flac \
+        -compression_level 0 \
+        -f flac \
+        -content_type audio/flac \
+        "$ICECAST_URL" 2>&1 || true
+    echo "[stream-relay] ffmpeg exited — reconnecting in 3s..."
+    sleep 3
+done