Introduces uniform column key concept for calendar events

Refactors column identification with a new buildColumnKey method to support flexible date and resource tracking

Replaces separate dateKey and resourceId handling with a unified columnKey approach
Improves column rendering and event management with more consistent key generation
Simplifies cross-component event tracking and column lookups

src/v2/core/DateService.ts

@@ -52,6 +52,48 @@ export class DateService {
     return this.formatDate(date);
   }
 
+  // ============================================
+  // COLUMN KEY
+  // ============================================
+
+  /**
+   * Build a uniform columnKey from grouping segments
+   * Handles any combination of date, resource, team, etc.
+   *
+   * @example
+   * buildColumnKey({ date: '2025-12-09' }) → "2025-12-09"
+   * buildColumnKey({ date: '2025-12-09', resource: 'EMP001' }) → "2025-12-09:EMP001"
+   */
+  buildColumnKey(segments: Record<string, string>): string {
+    // Always put date first if present, then other segments alphabetically
+    const date = segments.date;
+    const others = Object.entries(segments)
+      .filter(([k]) => k !== 'date')
+      .sort(([a], [b]) => a.localeCompare(b))
+      .map(([, v]) => v);
+
+    return date ? [date, ...others].join(':') : others.join(':');
+  }
+
+  /**
+   * Parse a columnKey back into segments
+   * Assumes format: "date:resource:..." or just "date"
+   */
+  parseColumnKey(columnKey: string): { date: string; resource?: string } {
+    const parts = columnKey.split(':');
+    return {
+      date: parts[0],
+      resource: parts[1]
+    };
+  }
+
+  /**
+   * Extract dateKey from columnKey (first segment)
+   */
+  getDateFromColumnKey(columnKey: string): string {
+    return columnKey.split(':')[0];
+  }
+
   // ============================================
   // TIME CALCULATIONS
   // ============================================