Refactors UI components with new card header structure

Replaces `swp-section-label` with standardized `swp-card-header` and `swp-card-title`

Improves component consistency across multiple features:
- Adds structured card headers
- Introduces more semantic HTML elements
- Enhances layout and readability of card components

Updates CSS and component styles to support new structure

PlanTempus.Application/Features/Settings/Components/SettingsPayments/Default.cshtml

@@ -63,7 +63,7 @@
     </swp-card>
 
     <!-- Column 2: Online betaling + Gebyr -->
-    <div class="stacked-cards">
+    <swp-card-column>
         <!-- Online betaling -->
         <swp-card>
             <swp-card-header>
@@ -137,5 +137,5 @@
                 </swp-toggle-row>
             </swp-card-content>
         </swp-card>
-    </div>
+    </swp-card-column>
 </swp-two-column-grid>