Adds hierarchical grouping and entity resolution support

Enhances calendar rendering with dynamic parent-child relationships between entities

Introduces EntityResolver for dot-notation references
Supports belongsTo configuration in grouping
Implements flexible filtering across hierarchical entities

Improves rendering flexibility for complex organizational structures

src/v2/storage/teams/TeamService.ts

@@ -0,0 +1,44 @@
+import { ITeam, EntityType, IEventBus } from '../../types/CalendarTypes';
+import { TeamStore } from './TeamStore';
+import { BaseEntityService } from '../BaseEntityService';
+import { IndexedDBContext } from '../IndexedDBContext';
+
+/**
+ * TeamService - CRUD operations for teams in IndexedDB
+ *
+ * Teams define which resources belong together for hierarchical grouping.
+ * Extends BaseEntityService for standard entity operations.
+ */
+export class TeamService extends BaseEntityService<ITeam> {
+  readonly storeName = TeamStore.STORE_NAME;
+  readonly entityType: EntityType = 'Team';
+
+  constructor(context: IndexedDBContext, eventBus: IEventBus) {
+    super(context, eventBus);
+  }
+
+  /**
+   * Get teams by IDs
+   */
+  async getByIds(ids: string[]): Promise<ITeam[]> {
+    if (ids.length === 0) return [];
+    const results = await Promise.all(ids.map(id => this.get(id)));
+    return results.filter((t): t is ITeam => t !== null);
+  }
+
+  /**
+   * Build reverse lookup: resourceId → teamId
+   */
+  async buildResourceToTeamMap(): Promise<Record<string, string>> {
+    const teams = await this.getAll();
+    const map: Record<string, string> = {};
+
+    for (const team of teams) {
+      for (const resourceId of team.resourceIds) {
+        map[resourceId] = team.id;
+      }
+    }
+
+    return map;
+  }
+}