Refactor calendar rendering with RenderBuilder

Simplifies calendar rendering process by introducing a new RenderBuilder pattern

Improves flexibility and modularity of grouping renderer chain
Decouples rendering logic from specific grouping types
Enables dynamic column span calculation and recursive rendering

Reduces complexity in CalendarOrchestrator
Enhances type safety and simplifies renderer interfaces

src/v2/core/RenderBuilder.ts

@@ -0,0 +1,82 @@
+import { from, IEnumerable } from 'ts-linq-light';
+import { IGroupingRenderer, RenderContext } from './IGroupingRenderer';
+
+export interface NextFunction {
+  count(items: IEnumerable<unknown>): number;
+  render(items: IEnumerable<unknown>): void;
+}
+
+export interface RenderData {
+  teams?: IEnumerable<unknown>;
+  resources?: IEnumerable<unknown>;
+  dates?: IEnumerable<unknown>;
+}
+
+interface RenderLevel {
+  renderer: IGroupingRenderer;
+  items: IEnumerable<unknown>;
+}
+
+export class RenderBuilder {
+  private levels: RenderLevel[] = [];
+
+  constructor(
+    private context: RenderContext,
+    private data: RenderData
+  ) {}
+
+  add(renderer: IGroupingRenderer, items: IEnumerable<unknown>): this {
+    this.levels.push({ renderer, items });
+    return this;
+  }
+
+  getTotalCount(): number {
+    if (this.levels.length === 0) return 0;
+
+    const chain = this.buildChain(0);
+    return chain.count(this.levels[0].items);
+  }
+
+  build(): void {
+    if (this.levels.length === 0) return;
+
+    const chain = this.buildChain(0);
+    chain.render(this.levels[0].items);
+  }
+
+  private buildChain(index: number): NextFunction {
+    if (index >= this.levels.length) {
+      // Leaf - ingen flere levels
+      return {
+        count: (items) => from(items).count(),
+        render: () => {}
+      };
+    }
+
+    const level = this.levels[index];
+    const nextChain = this.buildChain(index + 1);
+
+    return {
+      count: (items) => {
+        let total = 0;
+        for (const item of items) {
+          const childItems = this.getChildItems(index, item);
+          total += nextChain.count(childItems);
+        }
+        return total || from(items).count();
+      },
+      render: (items) => {
+        level.renderer.render(items, this.data, nextChain, this.context);
+      }
+    };
+  }
+
+  private getChildItems(levelIndex: number, _parentItem: unknown): IEnumerable<unknown> {
+    // Returnerer næste levels items - rendereren selv filtrerer baseret på parent
+    const nextLevel = this.levels[levelIndex + 1];
+    if (!nextLevel) {
+      return from([]);
+    }
+    return nextLevel.items;
+  }
+}