Improve UI components and styling consistency

- Make AddButton component generic with href prop instead of hardcoded path
- Update PaymentModal with Nord theme styling and improved UX
- Add EditButton functionality to PaymentModal
- Remove old recurring payment add pages that are no longer needed
- Update all AddButton usages across rezepte and cospend pages
- Add AddButton to cospend dashboard for better navigation

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/routes/rezepte/tips-and-tricks/+page.svelte

@@ -59,4 +59,4 @@ h1{
 </p>
 </div>
 
-<AddButton></AddButton>
+<AddButton href="/rezepte/add"></AddButton>