Add pure-ffmpeg RTSP capture and camera audio for sunrise videos

Removes dependency on MotionEye or any NVR software.  Everything is now
CLI/ffmpeg configured entirely from sky-cam.conf.

capture.sh
  Long-running systemd service (one per camera) that pulls frames from the
  camera's RTSP stream at CAPTURE_INTERVAL seconds, writing HH-MM-SS.jpg
  into BASE_DIR/<cam>/YYYY-MM-DD/.  Restarts at midnight for the new date
  directory; auto-reconnects on camera disconnect.

sunrise-audio-capture.sh
  One-shot service triggered at 03:00.  Waits until (sunrise minus
  SUNRISE_PRE_MIN minus AUDIO_PRE_BUFFER_MIN), then records the RTSP audio
  stream for the full sunrise window.  Output deleted after mixing.

daily_sunrise_video.sh
  Step 3 now mixes in sunrise-audio.m4a when AUDIO_ENABLED=true and the
  file exists.  Audio is centred on actual sunrise time at natural speed
  while the video plays as the sped-up timelapse.  Uses filter_complex
  when audio is present (can't combine -vf with -filter_complex).

install.sh
  Generates sky-cam-capture-<cam>.service for each camera with CAM_RTSP_<cam>
  set, and sky-cam-audio-capture.{service,timer} when AUDIO_ENABLED=true.

sky-cam.conf
  New settings: CAM_RTSP_<cam>, CAPTURE_INTERVAL, AUDIO_ENABLED,
  AUDIO_PRE_BUFFER_MIN, CAPTURE_AUDIO_BITRATE.

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

install.sh

@@ -111,6 +111,50 @@ write_timer "sky-cam-sunrise" "$SUNRISE_CAM: daily sunrise video" "$SCHEDULE_SUN
 
 timers=(sky-cam-sunrise)
 
+# ── Per-camera continuous capture services ────────────────────────────────────
+# capture.sh replaces MotionEye / any NVR for periodic JPEG capture.
+# Generated when CAM_RTSP_<cam> is set; Type=simple (long-running, not oneshot).
+capture_services=()
+for cam in "${CAMERAS[@]}"; do
+    rtsp_var="CAM_RTSP_${cam}"
+    if [ -n "${!rtsp_var:-}" ]; then
+        cat > "$UNIT_DIR/sky-cam-capture-${cam}.service" <<EOF
+[Unit]
+Description=Sky-Cam — ${cam}: continuous RTSP frame capture
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+ExecStart=$SCRIPT_DIR/capture.sh ${cam}
+Restart=on-failure
+RestartSec=30
+StandardOutput=journal
+StandardError=journal
+
+[Install]
+WantedBy=default.target
+EOF
+        echo "  wrote sky-cam-capture-${cam}.service"
+        capture_services+=("sky-cam-capture-${cam}")
+    else
+        echo "  WARNING: CAM_RTSP_${cam} not set — skipping capture service for ${cam}"
+        echo "           (set CAM_RTSP_${cam}=rtsp://... in sky-cam.conf to enable)"
+    fi
+done
+
+# ── Sunrise audio capture ─────────────────────────────────────────────────────
+# Triggered at 03:00; waits internally until the right time before recording.
+if [ "${AUDIO_ENABLED:-false}" = "true" ]; then
+    write_service "sky-cam-audio-capture" \
+        "$SUNRISE_CAM: sunrise audio capture" \
+        "sunrise-audio-capture.sh"
+    write_timer "sky-cam-audio-capture" \
+        "$SUNRISE_CAM: sunrise audio capture" \
+        "03:00:00"
+    timers+=("sky-cam-audio-capture")
+fi
+
 # ── Per-camera Four Seasons and full-day jobs ─────────────────────────────────
 # Reads CAMERAS, SCHEDULE_SEASONS_<cam>, SCHEDULE_FULLDAY_<cam> from sky-cam.conf.
 # Scripts receive the camera name as $1 so they know which camera to process.
@@ -146,6 +190,12 @@ done
 echo ""
 $SC daemon-reload
 
+for svc in "${capture_services[@]}"; do
+    $SC enable --now "${svc}.service" \
+        && echo "  enabled + started ${svc}.service" \
+        || echo "  WARNING: could not enable ${svc}.service"
+done
+
 for timer in "${timers[@]}"; do
     $SC enable --now "${timer}.timer" \
         && echo "  enabled + started ${timer}.timer" \