refactor(web): convert timeline layout options to derived state

- Replace createLayoutOptions() method with derived layoutOptions property for better reactivity. 
- Remove duplicate refreshLayout() implementation 
- Simplify setLayoutOptions() by removing unnecessary change tracking.

web/src/lib/managers/timeline-manager/internal/layout-support.svelte.ts

@@ -34,7 +34,7 @@ export function layoutMonthGroup(timelineManager: TimelineManager, month: MonthG
   let dayGroupRow = 0;
   let dayGroupCol = 0;
 
-  const options = timelineManager.createLayoutOptions();
+  const options = timelineManager.layoutOptions;
   for (const dayGroup of month.dayGroups) {
     dayGroup.layout(options, noDefer);
 

web/src/lib/managers/timeline-manager/timeline-manager.svelte.ts

@@ -14,7 +14,6 @@ import { isEqual } from 'lodash-es';
 import { SvelteDate, SvelteMap, SvelteSet } from 'svelte/reactivity';
 
 import { PhotostreamManager } from '$lib/managers/photostream-manager/PhotostreamManager.svelte';
-import { updateGeometry } from '$lib/managers/timeline-manager/internal/layout-support.svelte';
 import {
   addAssetsToMonthGroups,
   runAssetOperation,
@@ -264,13 +263,6 @@ export class TimelineManager extends PhotostreamManager {
     return [...unprocessedIds];
   }
 
-  refreshLayout() {
-    for (const month of this.months) {
-      updateGeometry(this, month, { invalidateHeight: true });
-    }
-    this.updateIntersections();
-  }
-
   getFirstAsset(): TimelineAsset | undefined {
     return this.months[0]?.getFirstAsset();
   }