Vue Frontend base setup

[wisskirchenj]

Do the base work for Frontend setup like:

• definition and setup of a suitable folder structure (within src/) for views, composables, router, assets, feature groups, etc.. ✅
• deciding on client to use for REST calls to server - and integrating it ✅ (axios)
• inject service keys and composables to use the client Rest services => separate issue
• setup App.vue and main.js including vue-router ✅
• define the MainLayout vue slot, where all views get rendered into ✅
• provide a first CardDetails.vue view using suitable Vuetify components to display cards => #16 (make this view already customizable enough - e.g. readOnly prop - to reuse it as entry form page to insert new cards)
• define first composables for common error handling ✅

[wisskirchenj]

so remaining tasks here are only:

• inject service keys and composables to use the axios client Rest services
• define first composables for common error handling (which can be done at a later point)

[wisskirchenj]

closed as > 90% is completed - and remaining will get into new issue