add gitkeep build folder

Signed-off-by: Sam Therapy <sam@samtherapy.net>

.drone.jsonnet

@@ -17,7 +17,7 @@ local testing(version, arch) = {
       name: 'lint-frontend',
       image: 'guergeiro/pnpm',
       commands: [
-        'pnpm i',
+        'pnpm i -F frontend',
         'make lint-frontend',
       ],
     },

frontend/.gitignore

@@ -1,6 +1,7 @@
 .DS_Store
 node_modules
-/build
+build/*
+!build/.gitkeep
 /.svelte-kit
 /package
 .env