setup yarn scripts and added new commands to build script

Dockerfile

@@ -4,10 +4,8 @@ WORKDIR /build
 COPY . /build
 RUN mkdir /build/public/js
 RUN mkdir /build/public/css
-RUN npm install -g sass
-RUN npm install -g typescript
-RUN tsc
-RUN sass scss/:public/css --style=compressed --no-source-map
+RUN yarn init
+RUN yarn compile
 
 # Prepare Webserver
 ARG INSTALL_CRON=0

package.json

@@ -5,6 +5,11 @@
   "repository": "git@gitlab.jonasled.de:jonasled/website.git",
   "author": "jonasled <git@jonasled.de>",
   "license": "LGPL-3.0-or-later",
+  "scripts": {
+    "compile": "concurrently \"yarn css\" \"yarn js\"",
+    "css": "sass scss/:public/css --style=compressed --no-source-map",
+    "js": "tsc"
+  },
   "devDependencies": {
     "@types/node": "^14.14.31",
     "sass": "^1.32.8",