perf(api): eliminate N+1 queries, add query guards and missing indexes

- Notification fan-out: replace sequential for loops with Promise.all (allocation-effects, notification-broadcast, create-notification)
- Public holiday batch: group resources by location combo, resolve holidays once per group, replace per-holiday delete/findFirst/create with 3 batched queries (~18K → ~5 queries)
- Add take guards to unbounded findMany calls (resource-analytics: 5000, resource-marketplace: 2000, resource-capacity: 1000, chargeability-report: 2000)
- auto-staffing: add select with only needed fields + take: 5000
- schema.prisma: add 5 missing indexes (ManagementLevel.groupId, Blueprint.isActive/target, Comment.parentId, Vacation.requestedById, Resource.managementLevelGroupId)

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

packages/api/src/lib/auto-staffing.ts

@@ -54,6 +54,22 @@ type DbClient = Parameters<typeof listAssignmentBookings>[0] & {
   resource: {
     findMany: (args: {
       where: { isActive: true };
+      select?: {
+        id?: true;
+        displayName?: true;
+        eid?: true;
+        skills?: true;
+        lcrCents?: true;
+        chargeabilityTarget?: true;
+        valueScore?: true;
+        availability?: true;
+        countryId?: true;
+        federalState?: true;
+        metroCityId?: true;
+        country?: { select: { code: true } };
+        metroCity?: { select: { name: true } };
+      };
+      take?: number;
     }) => Promise<Array<{
       id: string;
       displayName: string;
@@ -155,6 +171,22 @@ export async function generateAutoSuggestions(
     // 4. Fetch all active resources and their current bookings
     const resources = await db.resource.findMany({
       where: { isActive: true },
+      select: {
+        id: true,
+        displayName: true,
+        eid: true,
+        skills: true,
+        lcrCents: true,
+        chargeabilityTarget: true,
+        valueScore: true,
+        availability: true,
+        countryId: true,
+        federalState: true,
+        metroCityId: true,
+        country: { select: { code: true } },
+        metroCity: { select: { name: true } },
+      },
+      take: 5000,
     });
 
     if (resources.length === 0) return;

packages/api/src/lib/create-notification.ts

@@ -93,10 +93,7 @@ export async function createNotificationsForUsers(
   params: Omit<CreateNotificationParams, "userId"> & { userIds: string[] },
 ): Promise<number> {
   const { userIds, ...rest } = params;
-  let count = 0;
-  for (const userId of userIds) {
-    await createNotification({ ...rest, userId });
-    count++;
-  }
-  return count;
+  if (userIds.length === 0) return 0;
+  await Promise.all(userIds.map((userId) => createNotification({ ...rest, userId })));
+  return userIds.length;
 }