test(dashboard): add Playwright e2e scaffolding with smoke spec

Milestone A of the frontend test plan. Sets up the test rig — config,
globalSetup that probes the backend and seeds an admin session into
storageState, lightweight fixtures, and a 3-test smoke spec — without
yet covering any user journeys (those land in Milestone B).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

dashboard/tests/e2e/fixtures/cleanup.ts

@@ -0,0 +1,48 @@
+import type { APIRequestContext } from '@playwright/test';
+import { adminApi } from './api';
+
+// Resources to delete after a test, in LIFO order. Tests register
+// their creations and the registry tears everything down in
+// `cleanupRegistered` — typically called from `test.afterEach`.
+
+type Cleanup = (api: APIRequestContext) => Promise<void>;
+
+export class CleanupRegistry {
+	private items: Cleanup[] = [];
+
+	app(slugOrId: string): void {
+		this.items.push(async (api) => {
+			await api.delete(`/api/v1/admin/apps/${encodeURIComponent(slugOrId)}?force=true`);
+		});
+	}
+
+	adminUser(userId: string): void {
+		this.items.push(async (api) => {
+			await api.delete(`/api/v1/admin/admins/${userId}`);
+		});
+	}
+
+	apiKey(keyId: string): void {
+		this.items.push(async (api) => {
+			await api.delete(`/api/v1/admin/api-keys/${keyId}`);
+		});
+	}
+
+	async run(): Promise<void> {
+		if (this.items.length === 0) return;
+		const api = await adminApi();
+		try {
+			for (const item of this.items.reverse()) {
+				try {
+					await item(api);
+				} catch {
+					// Best-effort cleanup — a missing resource (already
+					// deleted by the test) shouldn't fail the suite.
+				}
+			}
+		} finally {
+			await api.dispose();
+			this.items = [];
+		}
+	}
+}