Add recording cleanup container to remove noise files

Alpine-based sdr-cleanup container runs a find loop every 5 minutes,
deleting MP3 files under 3 KB (configurable via SIZE_THRESHOLD env var)
to keep the web browser and Samba share free of false-positive recordings.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cleanup-recordings.sh

@@ -0,0 +1,16 @@
+#!/bin/sh
+# Deletes small MP3 recordings that are likely noise/false positives.
+# Runs in a loop, intended for use inside a Docker container.
+#
+# Environment variables:
+#   SIZE_THRESHOLD  - find -size format, e.g. 3k, 5k, 10k (default: 3k)
+#   INTERVAL        - seconds between runs (default: 300)
+
+RECORDINGS_DIR="/recordings"
+SIZE_THRESHOLD="${SIZE_THRESHOLD:-3k}"
+INTERVAL="${INTERVAL:-300}"
+
+while true; do
+  find "$RECORDINGS_DIR" -type f -name '*.mp3' -size "-${SIZE_THRESHOLD}" -mmin +1 -delete
+  sleep "$INTERVAL"
+done