Renders all-day events based on header data

Refactors all-day event rendering to use header column data.
This ensures events are rendered based on the actual visible
dates in the header, improving accuracy and responsiveness to view changes.

Removes direct dependency on week dates in `AllDayManager` and
`EventRenderingService`, instead, the all-day manager is instantiated
with event manager.

Updates `HeaderManager` to emit header bounds.

src/utils/ColumnDetectionUtils.ts

@@ -87,4 +87,32 @@ export class ColumnDetectionUtils {
     public static getColumns(): ColumnBounds[] {
         return [...this.columnBoundsCache];
     }
+    public static getHeaderColumns(): ColumnBounds[] {
+        
+        let dayHeaders: ColumnBounds[] = [];
+
+        const dayColumns = document.querySelectorAll('swp-calendar-header swp-day-header');
+        let index = 1;
+        // Cache hver kolonnes x-grænser
+        dayColumns.forEach(column => {
+            const rect = column.getBoundingClientRect();
+            const date = (column as HTMLElement).dataset.date;
+
+            if (date) {
+                dayHeaders.push({
+                    boundingClientRect : rect,
+                    element: column as HTMLElement,
+                    date,
+                    left: rect.left,
+                    right: rect.right, 
+                    index: index++
+                });
+            }
+        });
+
+        // Sorter efter x-position (fra venstre til højre)
+        dayHeaders.sort((a, b) => a.left - b.left);
+        return dayHeaders;
+
+    }
 }