Adds Kasse (Cash Register) module and related components

Introduces comprehensive cash management functionality with multiple view components for tracking daily transactions, filtering, and reconciliation

Implements:
- Cash calculation and difference tracking
- Dynamic tab switching
- Checkbox selection and row expansion
- Date filtering and approval mechanisms

PlanTempus.Application/Features/Kasse/Components/KasseDifference/Default.cshtml

@@ -0,0 +1,7 @@
+<swp-difference-box id="differenceBox" class="neutral">
+    <swp-difference-label>
+        Kontant difference
+        <small>Optalt minus forventet</small>
+    </swp-difference-label>
+    <swp-difference-value id="differenceValue">– kr</swp-difference-value>
+</swp-difference-box>

PlanTempus.Application/Features/Kasse/Components/KasseDifference/KasseDifferenceViewComponent.cs

@@ -0,0 +1,15 @@
+using Microsoft.AspNetCore.Mvc;
+
+namespace PlanTempus.Application.Features.Kasse.Components;
+
+/// <summary>
+/// ViewComponent for displaying the cash difference.
+/// Shows positive/negative/neutral states with color coding.
+/// </summary>
+public class KasseDifferenceViewComponent : ViewComponent
+{
+    public IViewComponentResult Invoke()
+    {
+        return View();
+    }
+}