Normalize and improve font sizes

This commit standardizes font sizes across components for a uniform
look. The icon sizes, font weights and line heights are also adjusted
accordingly for better standardization and simplicity.

- Introduce variables for standard font sizes, enhancing
  maintainability.
- Remove explicit pixel values, replaced with scalable units based on
  root size.
- Remove workaround for line-height adoptation of bigger font-size.
- Use consistent small font-size for the code area.
- Adjust checkbox tick to scale with font size.

src/presentation/components/Scripts/View/Cards/CardSelectionIndicator.vue

@@ -1,5 +1,5 @@
 <template>
-  <div>
+  <div class="icon">
     <AppIcon
       v-if="isAnyChildSelected && !areAllChildrenSelected"
       icon="battery-half"
@@ -53,3 +53,10 @@ export default defineComponent({
 });
 
 </script>
+
+<style scoped lang="scss">
+@use "@/presentation/assets/styles/main" as *;
+.icon {
+  font-size: $font-size-normal;
+}
+</style>