fix: add ability to fetch stock images on startup in dockerfile (#324)

Author: gbbirkisson

docker/docker-entrypoint.d/60-stock-images.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env sh
+
+if [ ! -z "$SPIS_MEDIA_FETCH_STOCK" ]; then
+    SPIS_MEDIA_STOCK_DIR="$SPIS_MEDIA_DIR/stock"
+
+    if [ ! -d "$SPIS_MEDIA_STOCK_DIR" ]; then
+        echo "Starting to fetch $SPIS_MEDIA_FETCH_STOCK stock images"
+
+        mkdir -p "$SPIS_MEDIA_STOCK_DIR"
+
+        for i in $(seq $SPIS_MEDIA_FETCH_STOCK); do
+            curl -s -L -o "$SPIS_MEDIA_STOCK_DIR/${i}.jpg" https://picsum.photos/800/600
+        done
+
+        echo "Done fetching $SPIS_MEDIA_FETCH_STOCK stock images"
+    fi
+fi