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/wwwroot/css/tabs.css

@@ -0,0 +1,94 @@
+/**
+ * Tabs - Tab Bar Navigation
+ *
+ * Horizontal tab bar with underline active state
+ * Based on POC: poc-indstillinger.html
+ */
+
+/* ===========================================
+   TAB BAR
+   =========================================== */
+swp-tab-bar {
+  display: flex;
+  gap: 0;
+  background: var(--color-surface);
+  border-bottom: 1px solid var(--color-border);
+  padding: 0 var(--spacing-12);
+  position: sticky;
+  top: var(--topbar-height);
+  z-index: var(--z-sticky);
+}
+
+/* Account for demo banner if present */
+body.has-demo-banner swp-tab-bar {
+  top: calc(var(--topbar-height) + 40px);
+}
+
+/* ===========================================
+   TAB ITEM
+   =========================================== */
+swp-tab {
+  display: flex;
+  align-items: center;
+  gap: var(--spacing-4);
+  padding: var(--spacing-7) var(--spacing-12);
+  font-size: var(--font-size-base);
+  font-weight: var(--font-weight-medium);
+  color: var(--color-text-secondary);
+  cursor: pointer;
+  border-bottom: 2px solid transparent;
+  margin-bottom: -1px;
+  transition: all var(--transition-fast);
+}
+
+swp-tab i {
+  font-size: var(--font-size-xl);
+}
+
+swp-tab:hover {
+  color: var(--color-text);
+  background: var(--color-background-alt);
+}
+
+swp-tab.active {
+  color: var(--color-teal);
+  border-bottom-color: var(--color-teal);
+}
+
+swp-tab.active:hover {
+  background: transparent;
+}
+
+/* ===========================================
+   TAB CONTENT
+   =========================================== */
+swp-tab-content {
+  display: none;
+}
+
+swp-tab-content.active {
+  display: block;
+}
+
+/* ===========================================
+   TAB WITH BADGE
+   =========================================== */
+swp-tab swp-badge {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  min-width: 20px;
+  height: 20px;
+  padding: 0 var(--spacing-2);
+  margin-left: var(--spacing-2);
+  font-size: var(--font-size-xs);
+  font-weight: var(--font-weight-semibold);
+  border-radius: var(--radius-full);
+  background: var(--color-background-alt);
+  color: var(--color-text-secondary);
+}
+
+swp-tab.active swp-badge {
+  background: color-mix(in srgb, var(--color-teal) 15%, transparent);
+  color: var(--color-teal);
+}