feat: import pg-aggregates plugin with Constructive adaptations

graphile/graphile-pg-aggregates/.gitignore

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+dist
+node_modules
+
+# yarn stuff
+.yarn/*
+!.yarn/releases
+!.yarn/releases/*
+!.yarn/plugins
+!.yarn/plugins/*
+!.yarn/patches
+!.yarn/patches/*

graphile/graphile-pg-aggregates/README.md

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+# graphile-pg-aggregates
+
+<p align="center" width="100%">
+  <img height="250" src="https://raw.githubusercontent.com/constructive-io/constructive/refs/heads/main/assets/outline-logo.svg" />
+</p>
+
+<p align="center" width="100%">
+  <a href="https://github.com/constructive-io/constructive/actions/workflows/run-tests.yaml">
+    <img height="20" src="https://github.com/constructive-io/constructive/actions/workflows/run-tests.yaml/badge.svg" />
+  </a>
+   <a href="https://github.com/constructive-io/constructive/blob/main/LICENSE"><img height="20" src="https://img.shields.io/badge/license-MIT-blue.svg"/></a>
+   <a href="https://www.npmjs.com/package/graphile-pg-aggregates"><img height="20" src="https://img.shields.io/github/package-json/v/constructive-io/constructive?filename=graphile%2Fgraphile-pg-aggregates%2Fpackage.json"/></a>
+</p>
+
+PostGraphile v5 aggregate plugin for the Constructive monorepo.
+
+Adds aggregate support to PostGraphile connections:
+
+- **Aggregates:** `sum`, `avg`, `min`, `max`, `stddevSample`, `stddevPopulation`, `varianceSample`, `variancePopulation`, `distinctCount`
+- **Grouped aggregates:** `groupedAggregates(groupBy: [...], having: {...})` on connections
+- **Order by aggregates:** Order parent connections by aggregates on related tables
+- **Filter by aggregates:** Filter parent connections by aggregate values on related tables (via connection-filter integration)
+- **Custom aggregates:** Register your own aggregate functions via the `pgAggregateSpecs` build extension
+- **Smart tags:** `@behavior -aggregates` to disable per-table
+
+> **Origin:** Forked from [`@graphile/pg-aggregates`](https://github.com/graphile/pg-aggregates) (v5 branch) by Benjie Gillam. Adapted for the Constructive connection-filter fork and build system.
+
+## Usage
+
+```typescript
+import { PgAggregatesPreset } from 'graphile-pg-aggregates';
+
+const preset: GraphileConfig.Preset = {
+  extends: [
+    PgAggregatesPreset,
+  ],
+};
+```
+
+Or via the `ConstructivePreset` which includes it automatically:
+
+```typescript
+import { ConstructivePreset } from 'graphile-settings';
+```
+
+## Example Query
+
+```graphql
+{
+  allOrders {
+    aggregates {
+      sum { total }
+      avg { total }
+      distinctCount { status }
+    }
+    groupedAggregates(groupBy: [STATUS]) {
+      keys
+      sum { total }
+    }
+  }
+}
+```
+
+## Per-Table Opt-Out
+
+Disable aggregates on a specific table via smart tags:
+
+```sql
+COMMENT ON TABLE my_table IS E'@behavior -aggregates';
+```