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/support/clients.ts

@@ -0,0 +1,45 @@
+// PocketBase SDK clients for tests; each helper returns its own instance with an in-memory auth store.
+import { randomUUID } from 'node:crypto';
+import PocketBase, { BaseAuthStore } from 'pocketbase';
+import { inject } from 'vitest';
+
+declare module 'vitest' {
+    export interface ProvidedContext {
+        pbUrl: string;
+        pbDataDir: string;
+        pbSuperuser: { email: string; password: string };
+    }
+}
+
+export interface TestUser {
+    id: string;
+    email: string;
+    password: string;
+}
+
+export function asGuest(): PocketBase {
+    return new PocketBase(inject('pbUrl'), new BaseAuthStore());
+}
+
+export async function asSuperuser(): Promise<PocketBase> {
+    const { email, password } = inject('pbSuperuser');
+    const pb = asGuest();
+    await pb.collection('_superusers').authWithPassword(email, password);
+    return pb;
+}
+
+export async function createUser(overrides: Record<string, unknown> = {}): Promise<TestUser> {
+    const data = { email: `user-${randomUUID()}@test.local`, password: randomUUID(), ...overrides };
+    const record = await (
+        await asSuperuser()
+    )
+        .collection('users')
+        .create({ ...data, passwordConfirm: data.password });
+    return { id: record.id, email: String(data.email), password: String(data.password) };
+}
+
+export async function asUser(user: TestUser): Promise<PocketBase> {
+    const pb = asGuest();
+    await pb.collection('users').authWithPassword(user.email, user.password);
+    return pb;
+}