Add ambient chunk as 2nd audio fallback; fix capture service exit-code bug

daily_sunrise_video.sh:
- Insert continuous ambient recording extract as 2nd fallback (after today's
  scheduled sunrise audio, before live RTSP).  Finds the chunk file in
  AUDIO_DIR/<cam>/<date>/ whose start time is the latest one at or before
  sunrise, then ffmpeg-copies SUNRISE_TARGET_SECS centred on sunrise_sec.
- Renumber remaining fallbacks: live RTSP → 3rd, yesterday → 4th, library → 5th.

sunrise-audio-capture.sh:
- Fix: retention find pipeline could exit non-zero (directory not yet created
  or permission error) and with set -euo pipefail cause the service to report
  status=1/FAILURE even after a successful capture.  Guard with [ -d ] and
  add || true so a retention failure never masks a successful recording.

https://claude.ai/code/session_01DANuzLCLhhQ7Li12RTcswY

sunrise-audio-capture.sh

@@ -86,11 +86,15 @@ size=$(du -h "$output" | cut -f1)
 echo "Audio capture complete: $output  (${record_dur_sec}s, $size)"
 
 # Rolling retention for sunrise audio clips
+# Guard with [ -d ] so find never exits non-zero under set -euo pipefail,
+# which would cause the service to report failure even after a clean capture.
 retain="${SUNRISE_AUDIO_RETENTION_DAYS:-7}"
 if [ "$retain" -gt 0 ]; then
     audio_root="${AUDIO_DIR:-$BASE_DIR/audio}/sunrise/$CAM"
-    deleted=$(find "$audio_root" -name "sunrise-audio.m4a" -mtime +"$retain" -print -delete 2>/dev/null | wc -l)
-    [ "$deleted" -gt 0 ] && echo "Retention: deleted $deleted sunrise audio clip(s) older than ${retain}d" || true
+    if [ -d "$audio_root" ]; then
+        deleted=$(find "$audio_root" -name "sunrise-audio.m4a" -mtime +"$retain" -print -delete 2>/dev/null | wc -l) || true
+        [ "$deleted" -gt 0 ] && echo "Retention: deleted $deleted sunrise audio clip(s) older than ${retain}d" || true
+    fi
 fi
 
 exit 0