feat: integrate CampusScope.filter() into all business services (12 services + 12 modules)

apps/server/src/common/campus-scope.ts

@@ -49,6 +49,13 @@ export class CampusScope {
     return { ...where, departmentId: In(ids) } as unknown as T;
   }
 
+  /** Returns department IDs for QueryBuilder .andWhere() usage. null = no filtering needed. */
+  async getScopeDepartmentIds(): Promise<number[] | null> {
+    if (this.isSuperAdmin && !this.currentDepartmentId) return null;
+    const ids = await this.getEffectiveScopeIds();
+    return ids.length > 0 ? ids : null;
+  }
+
   private async getEffectiveScopeIds(): Promise<number[]> {
     // Specific campus selected → campus + descendants
     if (this.currentDepartmentId) {