Resume: restart an interrupted training instead of failing

The pipeline only reuses completed stages and refuses an incomplete training
directory. Remove it, so images and camera positions are reused and only the
training runs again.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/splat.sh

@@ -59,6 +59,16 @@ log=$RUNS_DIR/$slug.log
 mkdir -p "$RUNS_DIR"
 if [ "${FRESH:-0}" = 1 ]; then rm -rf "$out" "$log"; fi
 
+# The pipeline resumes finished stages only: an interrupted training run blocks --resume.
+# Then start the training over; images and camera positions are reused.
+manifest=$out/spirula/run.json
+if [[ " $* " == *" --resume "* ]] && [ -f "$manifest" ] && ! grep -q '"status": *"complete"' "$manifest"; then
+    ckpt=$(ls -d "$out"/spirula/training/step-*.ckpt 2>/dev/null | tail -1)
+    echo "Training was interrupted${ckpt:+ (last checkpoint: ${ckpt##*/step-})}; the pipeline cannot continue it." | tee -a "$log"
+    echo "Restarting the training, images and camera positions are reused." | tee -a "$log"
+    rm -rf "$out/spirula"
+fi
+
 # Image pairs from the duration: <per second>, clamped to the pipeline limits 100..500
 pairs() {
     local secs