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

daily_sunrise_video.sh

@@ -178,7 +178,7 @@ if $TEST_MODE; then
     sped_video=$(mktemp --suffix=-sped.mp4)
     echo "Step 2/3: speed-adjust (test)..."
 else
-    sped_video="$output_dir/$current_date-daily-sunrise-sped.mp4"
+    sped_video="$output_dir/$CAM_NAME-$current_date-daily-sunrise-sped.mp4"
     echo "Step 2/3: speed-adjust → $sped_video"
 fi
 if ! ffmpeg -loglevel warning \
@@ -275,9 +275,9 @@ fi
 if $TEST_MODE; then
     demo_dir="${DEMO_DIR:-$MOVIES_DIR/demoio}/$CAM_NAME"
     mkdir -p "$demo_dir"
-    final_video="$demo_dir/$current_date-daily-sunrise-test.mp4"
+    final_video="$demo_dir/$CAM_NAME-$current_date-daily-sunrise-test.mp4"
 else
-    final_video="$output_dir/$current_date-daily-sunrise.mp4"
+    final_video="$output_dir/$CAM_NAME-$current_date-daily-sunrise.mp4"
 fi
 fade_out=$(echo "scale=1; $SUNRISE_TARGET_SECS - 0.5" | bc)