perf(api): eliminate 3 N+1 query patterns

- timeline-holiday-load-support: deduplicate getResolvedCalendarHolidays
  by location key so resources sharing the same country/state/city resolve
  holidays once instead of per-resource
- rate-card-lookup: add lookupRatesBatch that loads rate card lines once
  and scores locally per demand line, replacing per-line DB round-trips
  in estimate-demand-lines autoFillDemandLineRates
- config-readmodels: include _count in utilization-category list query
  instead of calling getById per category for project counts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/api/src/router/utilization-category-procedure-support.ts

@@ -14,9 +14,11 @@ import {
   unsetDefaultUtilizationCategory,
 } from "./utilization-category-support.js";
 
-export const UtilizationCategoryListInputSchema = z.object({
-  isActive: z.boolean().optional(),
-}).optional();
+export const UtilizationCategoryListInputSchema = z
+  .object({
+    isActive: z.boolean().optional(),
+  })
+  .optional();
 
 export const UtilizationCategoryByIdInputSchema = z.object({
   id: z.string(),
@@ -38,6 +40,7 @@ export async function listUtilizationCategories(
   return ctx.db.utilizationCategory.findMany({
     where: buildUtilizationCategoryListWhere(input ?? {}),
     orderBy: { sortOrder: "asc" },
+    include: { _count: { select: { projects: true } } },
   });
 }