feat(FE): add primary button class

Author: Manuel Proß

web/src/styles/_btns.scss

@@ -0,0 +1,3 @@
+.btn-primary {
+    @apply border-solid border-[1px] rounded-xl border-secondary text-secondary py-3 px-6 transition-all hover:bg-secondary hover:text-white;
+}

web/src/styles/globals.scss

@@ -1,5 +1,6 @@
 @import './components.scss';
 @import './text.scss';
+@import './btns.scss';
 @tailwind base;
 @tailwind components;
 @tailwind utilities;