Prepend <cam> to all output filenames consistently

Audio:
  AUDIO_DIR/<cam>/YYYY-MM-DD/<cam>-HH-MM-SS.m4a

Movies — cam name now always leads the filename:
  daily_sunrise_video.sh:
    east-2026-04-22-daily-sunrise.mp4
    east-2026-04-22-daily-sunrise-sped.mp4  (intermediate)
    east-2026-04-22-daily-sunrise-test.mp4  (demo)
  4-seasons.sh:
    east-2026-04-21_Mvt2-Day2of31-final.mp4  (was: 2026-04-21_east_Mvt2-...)
  montage-mvt.sh:
    east-2026-03-20_Spring_Mvt1-Sped.mp4
    east-2026-03-20_Spring_Mvt1-Montage.mp4
  year-end-join.sh:
    east-2026.mp4  (already had cam at front)

sunrise2mm.py updated to look for the new east-YYYY-MM-DD-daily-sunrise.mp4
filename. Retention find patterns (wildcards) already match both formats.

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

ambient-record.sh

@@ -50,7 +50,7 @@ while true; do
     mkdir -p "$dir"
 
     timestamp=$(date +%H-%M-%S)
-    outfile="$dir/${timestamp}.m4a"
+    outfile="$dir/${CAM}-${timestamp}.m4a"
 
     echo "[$(date '+%Y-%m-%d %H:%M:%S')] Recording → $outfile  (${CHUNK}s)"