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/Services/Components/ServiceDetailDuration/Default.cshtml

@@ -2,8 +2,9 @@
 
 <swp-detail-grid>
     <swp-card>
-        <swp-section-label>@Model.LabelDurationVariants</swp-section-label>
-
+        <swp-card-header>
+            <swp-card-title>@Model.LabelDurationVariants</swp-card-title>
+        </swp-card-header>
         <swp-duration-list>
             @foreach (var variant in Model.DurationVariants)
             {
@@ -27,7 +28,9 @@
     </swp-card>
 
     <swp-card>
-        <swp-section-label>@Model.LabelBufferTimes</swp-section-label>
+        <swp-card-header>
+            <swp-card-title>@Model.LabelBufferTimes</swp-card-title>
+        </swp-card-header>
         <swp-edit-section>
             <swp-edit-row>
                 <swp-edit-label>@Model.LabelBufferBefore</swp-edit-label>