Improves event layout and stacking logic

Refactors the event layout and stacking logic based on review feedback.

This includes:
- Merging conflicting event groups to prevent inconsistencies.
- Implementing minimal stack level assignment using a min-heap.
- Consolidating styling and using DateService for drag operations.
- Adding reflow after drag and drop.
- Improving the column event filtering to include events overlapping midnight.
- Ensuring explicit sorting of events for grid layout.

scenarios/scenario-styles.css

@@ -0,0 +1,162 @@
+/* Shared styles for all scenario visualization files */
+
+body {
+  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
+  margin: 0;
+  padding: 20px;
+  background: #f5f5f5;
+}
+
+.scenario-container {
+  max-width: 1200px;
+  margin: 0 auto;
+  background: white;
+  padding: 30px;
+  border-radius: 8px;
+  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
+}
+
+h1, h2, h3 {
+  color: #333;
+  margin-top: 0;
+}
+
+.scenario-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  margin-bottom: 20px;
+  padding-bottom: 15px;
+  border-bottom: 2px solid #e0e0e0;
+}
+
+.scenario-title {
+  margin: 0;
+}
+
+.test-badge {
+  display: inline-block;
+  margin-left: 15px;
+  padding: 6px 14px;
+  border-radius: 6px;
+  font-weight: bold;
+  font-size: 14px;
+  vertical-align: middle;
+}
+
+.test-passed {
+  background: #4caf50;
+  color: white;
+}
+
+.test-failed {
+  background: #f44336;
+  color: white;
+}
+
+.test-pending {
+  background: #ff9800;
+  color: white;
+}
+
+.scenario-description {
+  background: #f8f9fa;
+  padding: 15px;
+  border-left: 4px solid #b53f7a;
+  margin-bottom: 20px;
+}
+
+.expected-result {
+  background: #e8f5e9;
+  padding: 12px;
+  border-radius: 4px;
+  margin: 15px 0;
+  font-family: 'Courier New', monospace;
+  font-size: 13px;
+}
+
+.calendar-column {
+  position: relative;
+  width: 350px;
+  height: 800px;
+  border: 2px solid #ddd;
+  border-radius: 8px;
+  background: white;
+  overflow: hidden;
+  margin: 20px 0;
+}
+
+/* Event styling */
+swp-event-group {
+  position: absolute;
+  left: 0;
+  right: 0;
+  display: flex;
+  gap: 4px;
+}
+
+swp-event-group > div {
+  flex: 1;
+  min-width: 0;
+}
+
+swp-event {
+  display: block;
+  padding: 8px;
+  border-left: 4px solid #b53f7a;
+  background: #fff3e0;
+  border-radius: 4px;
+  font-size: 12px;
+  overflow: hidden;
+  box-shadow: 0 1px 3px rgba(0,0,0,0.12);
+}
+
+swp-event-time {
+  display: block;
+  font-weight: bold;
+  margin-bottom: 4px;
+  color: #666;
+}
+
+swp-event-title {
+  display: block;
+  color: #333;
+}
+
+.back-link {
+  display: inline-block;
+  margin-bottom: 20px;
+  color: #b53f7a;
+  text-decoration: none;
+  font-weight: 500;
+}
+
+.back-link:hover {
+  text-decoration: underline;
+}
+
+.test-details {
+  margin-top: 20px;
+  padding: 15px;
+  background: #f8f9fa;
+  border-radius: 4px;
+  font-family: 'Courier New', monospace;
+  font-size: 13px;
+}
+
+.test-details h4 {
+  margin-top: 0;
+  color: #666;
+}
+
+.test-result-line {
+  padding: 4px 0;
+}
+
+.test-result-line.passed {
+  color: #4caf50;
+}
+
+.test-result-line.failed {
+  color: #f44336;
+}