chore(setup): Add and configure prettier (!4)

Co-authored-by: Phan Huy Tran <p.tran@neusta.de>
Reviewed-on: https://git.simonis.lol/projects/casino/pulls/4
Reviewed-by: Hop In, I Have Puppies AND WiFi <jleibl@noreply@simonis.lol>

frontend/package.json

@@ -6,7 +6,9 @@
     "start": "bunx @angular/cli serve --proxy-config src/proxy.conf.json",
     "build": "bunx @angular/cli build",
     "watch": "bunx @angular/cli build --watch --configuration development",
-    "test": "bunx @angular/cli test"
+    "test": "bunx @angular/cli test",
+    "format": "prettier --write \"src/**/*.{ts,html,css,scss}\"",
+    "format:check": "prettier --check \"src/**/*.{ts,html,css,scss}\""
   },
   "private": true,
   "dependencies": {
@@ -35,6 +37,7 @@
     "karma-coverage": "~2.2.0",
     "karma-jasmine": "~5.1.0",
     "karma-jasmine-html-reporter": "~2.1.0",
+    "prettier": "^3.4.2",
     "typescript": "~5.5.2"
   }
 }