Add event resize functionality with drag handles in week view

- Extend DragType enum to support ResizeEventStart and ResizeEventEnd operations
- Add visual resize handles at top/bottom edges of events for left-click resizing
- Implement start time resize by dragging top handle (preserves end time)
- Implement end time resize by dragging bottom handle (preserves start time)
- Add visual feedback with resizing event preview during drag operations
- Integrate resize operations with existing CalDAV update system
- Add CSS styling for resize handles with hover effects and resize cursors
- Maintain minimum 15-minute event duration during resize operations
- Preserve context menu functionality while preventing conflicts during drag
- Clean up code by removing experimental right-click drag functionality

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

styles.css

@@ -727,6 +727,93 @@ body {
     width: 100%;
 }
 
+/* Resizing event during drag */
+.temp-event-box.resizing-event {
+    background: inherit;
+    border: 2px solid rgba(255, 255, 255, 0.9);
+    color: white;
+    flex-direction: column;
+    align-items: flex-start;
+    justify-content: flex-start;
+    text-align: left;
+    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
+    transform: scale(1.01);
+}
+
+.temp-event-box.resizing-event .event-title {
+    font-weight: 600;
+    margin-bottom: 2px;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+    width: 100%;
+}
+
+.temp-event-box.resizing-event .event-time {
+    font-size: 0.65rem;
+    opacity: 0.9;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+    width: 100%;
+}
+
+/* Event resize zones and handles */
+.week-event {
+    position: relative;
+}
+
+.week-event .event-content {
+    padding: 2px;
+    height: 100%;
+    display: flex;
+    flex-direction: column;
+    justify-content: center;
+    pointer-events: auto;
+    z-index: 5;
+    position: relative;
+}
+
+/* Left-click drag handles */
+.resize-handle {
+    position: absolute;
+    left: 0;
+    right: 0;
+    height: 4px;
+    background: transparent;
+    cursor: ns-resize;
+    z-index: 10;
+    transition: background-color 0.2s;
+}
+
+.resize-handle-top {
+    top: 0;
+    border-top: 2px solid transparent;
+}
+
+.resize-handle-bottom {
+    bottom: 0;
+    border-bottom: 2px solid transparent;
+}
+
+.week-event:hover .resize-handle {
+    background: rgba(255, 255, 255, 0.3);
+}
+
+.week-event:hover .resize-handle-top {
+    border-top-color: rgba(255, 255, 255, 0.8);
+}
+
+.week-event:hover .resize-handle-bottom {
+    border-bottom-color: rgba(255, 255, 255, 0.8);
+}
+
+.resize-handle:hover {
+    background: rgba(255, 255, 255, 0.5) !important;
+    border-color: rgba(255, 255, 255, 1) !important;
+}
+
+
 .week-event .event-title {
     font-weight: 600;
     margin-bottom: 2px;