test(api): add temporary pocketbase harness for api tests

`pnpm test:api` starts an isolated PocketBase with project migrations and
hooks in a temp dir, provides SDK client helpers and cleans up after the run,
on failure and on SIGINT/SIGTERM. The superuser is generated per instance.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EvmtStx737hu8gXe15e55W

tests/api/global-setup.ts

@@ -0,0 +1,11 @@
+import type { TestProject } from 'vitest/node';
+import { startPocketBase } from '../support/pocketbase-server';
+import '../support/clients';
+
+export default async function setup(project: TestProject) {
+    const { url, dataDir, superuser, stop } = await startPocketBase();
+    project.provide('pbUrl', url);
+    project.provide('pbDataDir', dataDir);
+    project.provide('pbSuperuser', superuser);
+    return stop;
+}