fix(graphile-schema): route buildSchemaSDL pool through pg-cache for proper cleanup

Previously, buildSchemaSDL let makePgService create its own internal pg Pool
using a connection string. This pool was not tracked by pg-cache, so when
ephemeral database teardown called pgCache.delete() + dropdb, PostGraphile's
pool connections remained open, causing:

- 'database has active sessions' errors on dropdb
- pg_terminate_backend killing those connections
- 'terminating connection due to administrator command' (57P01) errors
  bubbling up to the user

Fix: Create the pool via getPgPool() (which registers it in pgCache) and pass
it directly to makePgService. Now the existing cleanup code in pgpm-module.ts
and generate.ts (pgCache.delete + waitForDisposals) properly closes the
PostGraphile pool before dropping the ephemeral database.

Author: pyramation

graphile/graphile-schema/src/build-schema.ts

@@ -2,7 +2,7 @@ import deepmerge from 'deepmerge'
 import { printSchema } from 'graphql'
 import { ConstructivePreset, makePgService } from 'graphile-settings'
 import { makeSchema } from 'graphile-build'
-import { buildConnectionString } from 'pg-cache'
+import { getPgPool } from 'pg-cache'
 import { getPgEnvOptions } from 'pg-env'
 import type { GraphileConfig } from 'graphile-config'
 
@@ -17,19 +17,18 @@ export async function buildSchemaSDL(opts: BuildSchemaOptions): Promise<string>
   const schemas = Array.isArray(opts.schemas) ? opts.schemas : []
 
   const config = getPgEnvOptions({ database })
-  const connectionString = buildConnectionString(
-    config.user,
-    config.password,
-    config.host,
-    config.port,
-    config.database,
-  )
+
+  // Create the pool through pg-cache so it is tracked and can be cleaned up
+  // by callers via pgCache.delete(database) before dropping ephemeral databases.
+  // Without this, makePgService creates its own internal pool that isn't released,
+  // causing "database has active sessions" errors during ephemeral DB teardown.
+  const pool = getPgPool(config)
 
   const basePreset: GraphileConfig.Preset = {
     extends: [ConstructivePreset],
     pgServices: [
       makePgService({
-        connectionString,
+        pool,
         schemas,
       }),
     ],