feat: add 11 new shopping icons and processing script

Add processed icons for glasnudeln, grünkohl, kokosnuss, lychee,
mangold, pak choi, pastinaken, reisnudeln, rettich, stroh 80, and
topinambur. Add ImageMagick script to remove Gemini watermark and
black background from raw icons. Update catalog and re-embed.

scripts/process-gemini-icons.sh

@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+# Process raw Gemini-generated shopping icons:
+# 1. Crop out the bottom-right watermark (sparkle)
+# 2. Remove solid black background → transparent
+# 3. Trim whitespace/transparent padding
+#
+# Usage: ./scripts/process-gemini-icons.sh [file...]
+#   No args: processes all unprocessed gemini_raw-*.png in static/shopping-icons/
+#   With args: processes only the specified raw files
+
+set -euo pipefail
+
+ICON_DIR="static/shopping-icons"
+
+# Collect files to process
+if [ $# -gt 0 ]; then
+  files=("$@")
+else
+  files=()
+  for raw in "$ICON_DIR"/gemini_raw-*.png; do
+    [ -f "$raw" ] || continue
+    name=$(basename "$raw" | sed 's/gemini_raw-//')
+    if [ ! -f "$ICON_DIR/$name" ]; then
+      files+=("$raw")
+    fi
+  done
+fi
+
+if [ ${#files[@]} -eq 0 ]; then
+  echo "No unprocessed icons found."
+  exit 0
+fi
+
+echo "Processing ${#files[@]} icon(s)..."
+
+for raw in "${files[@]}"; do
+  name=$(basename "$raw" | sed 's/gemini_raw-//')
+  out="$ICON_DIR/$name"
+
+  echo "  $name"
+
+  # Get image dimensions
+  dims=$(identify -format '%wx%h' "$raw")
+  w=${dims%x*}
+  h=${dims#*x}
+
+  # 1. Cover watermark sparkle in bottom-right with black
+  # 2. Remove all black → transparent
+  # 3. Trim transparent padding
+  wm_size=$(( w * 8 / 100 ))
+  wm_x=$(( w - wm_size ))
+  wm_y=$(( h - wm_size ))
+
+  magick "$raw" \
+    -fill black -draw "rectangle ${wm_x},${wm_y} ${w},${h}" \
+    -fuzz 25% -transparent black \
+    -trim +repage \
+    "$out"
+done
+
+echo "Done."