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

4-seasons.sh

@@ -106,7 +106,7 @@ echo "Raw duration: $raw_duration s"
 speed_factor=$(echo "scale=6; $raw_duration / $target_per_clip" | bc)
 echo "Step 2/2: speed factor $speed_factor..."
 
-final_file="$output_dir/${yesterday}_${CAM_NAME}_Mvt${MVT_NUM}-Day${DAY_OF_MVT}of${DAYS_IN_MVT}-final.mp4"
+final_file="$output_dir/${CAM_NAME}-${yesterday}_Mvt${MVT_NUM}-Day${DAY_OF_MVT}of${DAYS_IN_MVT}-final.mp4"
 if ! ffmpeg -loglevel warning \
     -i "$temp_video" \
     -vf "setpts=PTS/$speed_factor,fps=25" \