Degrade gracefully on overlay/audio failure; notify on upload success

Sunrise:
- Overlay failure no longer exits 1; the speed-only video is renamed to the
  expected final path so OnSuccess still fires and the upload still happens
- sunrise2mm.py now notifies on every upload outcome (success, post failure,
  file-not-found) via notify.sh so the user always knows whether the video
  reached Mattermost

Montage:
- Music+overlay failure no longer exits 1; the sped video is promoted to the
  *-Montage.mp4 path so year-end-join can still include this movement (as a
  silent, no-overlay clip) and the user is notified of the degraded output
- Year-end join trigger is now outside the success/failure branch so it fires
  in both cases

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

montage-mvt.sh

@@ -178,8 +178,9 @@ DT="${DT}:alpha='${ALPHA}':enable='${ENABLE}'"
 
 output_file="$output_dir/${MVT_START}_${SEASON}_Mvt${MVT_NUM}-Montage.mp4"
 
-# If this fails, $sped_file survives for manual recovery (re-run step 3 only).
-if ! ffmpeg -loglevel warning \
+# If music/overlay fails, the sped video is promoted to the output path so
+# year-end-join can still include this movement (as a silent, no-overlay clip).
+if ffmpeg -loglevel warning \
     -i "$sped_file" -i "$music_file" \
     -filter_complex \
 "[0:v]fade=t=in:st=0:d=${FADE_DUR},fade=t=out:st=${fade_out_start}:d=${FADE_DUR},${DT}[vout];\
@@ -187,20 +188,20 @@ if ! ffmpeg -loglevel warning \
     -map "[vout]" -map "[aout]" \
     -c:v libx264 -pix_fmt yuv420p -c:a aac -b:a "$AUDIO_BITRATE" \
     -t "$music_duration" -y "$output_file"; then
-    "$SCRIPT_DIR/notify.sh" "FAILED: montage step 3/3 (music+overlay) $SEASON Mvt$MVT_NUM ($ASTRO_YEAR)" \
-        "Music/overlay failed — sped video saved: $(basename "$sped_file")" || true
-    exit 1
+    rm -f "$sped_file"
+    echo "Done: $output_file"
+    "$SCRIPT_DIR/notify.sh" \
+        "Montage ready: $SEASON Mvt $MVT_NUM ($ASTRO_YEAR)" \
+        "$(basename "$output_file") — ${music_duration}s" \
+        || true
+else
+    mv "$sped_file" "$output_file"
+    echo "Music+overlay failed — silent video promoted to: $output_file"
+    "$SCRIPT_DIR/notify.sh" \
+        "WARNING: montage audio+overlay failed — $SEASON Mvt$MVT_NUM ($ASTRO_YEAR)" \
+        "Silent video saved as $(basename "$output_file") — re-run montage-mvt.sh to retry" || true
 fi
 
-rm -f "$sped_file"
-echo "Done: $output_file"
-
-# ── Notify ────────────────────────────────────────────────────────────────────
-"$SCRIPT_DIR/notify.sh" \
-    "Montage ready: $SEASON Mvt $MVT_NUM ($ASTRO_YEAR)" \
-    "$(basename "$output_file") — ${music_duration}s" \
-    || true   # notifications are best-effort
-
 # ── Trigger year-end join on last Autumn movement ────────────────────────────
 if [ "$SEASON" = "Autumn" ] && [ "$MVT_NUM" = "3" ]; then
     echo "Last movement of astronomical year $ASTRO_YEAR — triggering year-end join..."