Gate vendor.sh cache wipe behind QUARTO_SKIP_DENO_CACHE_WIPE

Default behavior unchanged: local ./configure.sh still wipes deno_cache
before re-vendoring. CI opts into cache preservation by setting
QUARTO_SKIP_DENO_CACHE_WIPE=1, enabling actions/cache to restore the
cache and have it survive vendor.sh.

Author: cderv

package/scripts/vendoring/vendor.sh

@@ -15,8 +15,9 @@ fi
 
 echo Revendoring quarto dependencies
 
-# remove deno_cache directory first
-if [ -d "$DENO_DIR" ]; then
+# remove deno_cache directory first, unless explicitly told to preserve
+# (CI sets QUARTO_SKIP_DENO_CACHE_WIPE=1 so a restored cache survives vendor.sh)
+if [ -d "$DENO_DIR" ] && [ "${QUARTO_SKIP_DENO_CACHE_WIPE}" != "1" ]; then
   rm -rf "$DENO_DIR"
 fi