Added check for commands to all scripts

build-functions/check-commands.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+NEEDED_COMMANDS="curl jq docker skopeo"
+for c in $NEEDED_COMMANDS; do
+  if ! command -v "$c" &>/dev/null; then
+    echo "⚠️  '$c' is not installed. Can't proceed with build."
+    exit 1
+  fi
+done