4-seasons: add progress reporting during validation and encoding

- Print "Validating N frames..." before the loop, including active
  filter thresholds when grey-checking is on
- Print "X / N frames checked..." every 500 frames so the user can
  see the loop is alive during the long ImageMagick pass
- Print "Validation done: N valid frames" after the loop
- Note "(may take several minutes)" on the Step 1 encode echo
- Show the speed factor and target together: "28.8x → 11.08s target"

https://claude.ai/code/session_01U29A8NpgJ41tboiggZNmk8

4-seasons.sh

@@ -103,8 +103,18 @@ mapfile -t all_images < <(find "$image_dir" -type f -name "*.jpg" | sort)
 GREY_MIN="${SEASONS_GREY_STDDEV_MIN:-0}"
 GREY_DARK_FLOOR="${SEASONS_GREY_DARK_FLOOR:-30}"
 LARGE_BYTES="${SEASONS_LARGE_FRAME_BYTES:-1048576}"  # files above this skip content check
-images=(); bad=0; grey=0
+total_frames=${#all_images[@]}
+images=(); bad=0; grey=0; checked=0
+if [ "$GREY_MIN" != "0" ]; then
+    echo "Validating $total_frames frames (grey-filter active: stddev<${GREY_MIN}, mean>${GREY_DARK_FLOOR})..."
+else
+    echo "Validating $total_frames frames..."
+fi
 for img in "${all_images[@]}"; do
+    ((checked++)) || true
+    if (( checked % 500 == 0 || checked == total_frames )); then
+        echo "  $checked / $total_frames frames checked..."
+    fi
     # Skip empty or unreadable files (0-byte writes from camera reconnects)
     if [ ! -r "$img" ] || [ ! -s "$img" ]; then
         echo "WARNING: skipping empty/missing frame: $(basename "$img")"
@@ -133,6 +143,7 @@ if [ "${#images[@]}" -eq 0 ]; then
     echo "ERROR: no valid images remain after filtering — skipping $yesterday."
     exit 0
 fi
+echo "Validation done: ${#images[@]} valid frames"
 
 for img in "${images[@]}"; do
     printf "file '%s'\nduration 0.04\n" "$img"
@@ -141,7 +152,7 @@ done > "$temp_file"
 printf "file '%s'\n" "${images[-1]}" >> "$temp_file"
 
 # ── Step 1: Build raw video ───────────────────────────────────────────────────
-echo "Step 1/2: encoding raw video from ${#images[@]} frames..."
+echo "Step 1/2: encoding raw video from ${#images[@]} frames (may take several minutes)..."
 ffmpeg -loglevel warning \
     -f concat -safe 0 -i "$temp_file" \
     -c:v libx264 -pix_fmt yuv420p -preset "$ENCODE_PRESET" -crf "$CRF_SEASONS_RAW" -vsync 2 -an \
@@ -152,7 +163,7 @@ echo "Raw duration: $raw_duration s"
 
 # ── Step 2: Speed-adjust to target clip duration ──────────────────────────────
 speed_factor=$(echo "scale=6; $raw_duration / $target_per_clip" | bc)
-echo "Step 2/2: speed factor $speed_factor..."
+echo "Step 2/2: speed factor ${speed_factor}x → ${target_per_clip}s target..."
 
 final_file="$output_dir/${CAM_NAME}-${yesterday}_Mvt${MVT_NUM}-Day${DAY_OF_MVT}of${DAYS_IN_MVT}-final.mp4"
 if ! ffmpeg -loglevel warning \