ui/phase-19: seed an authenticated session in the synthetic-report e2e

The root +layout.svelte redirects anonymous traffic to /login, so a
fresh CI browser context never gets to render the lobby's
DEV-gated synthetic-report section — the previous spec relied on
leftover session state in the local browser and silently broke on
clean runners (local-ci run 23).

Bootstrap the session through /__debug/store before navigating to
/lobby: load a device keypair, set a deterministic device session
id. The synthetic flow itself still bypasses the gateway entirely;
the seed only ensures `session.status === "authenticated"` so the
layout guard lets the lobby through.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ui/frontend/tests/e2e/inspector-ship-group.spec.ts

@@ -8,7 +8,35 @@
 // glue: lobby loader → in-memory registry → layout bypass → renderer
 // boot.
 
-import { expect, test } from "@playwright/test";
+import { expect, test, type Page } from "@playwright/test";
+
+interface DebugSurface {
+	ready: true;
+	loadSession(): Promise<unknown>;
+	setDeviceSessionId(id: string): Promise<void>;
+}
+
+declare global {
+	interface Window {
+		__galaxyDebug?: DebugSurface;
+	}
+}
+
+// Seed an authenticated session through `/__debug/store` so the
+// root layout's redirect-to-login guard passes. The synthetic flow
+// itself does not talk to the gateway, but the session check still
+// runs at every navigation.
+async function seedSession(page: Page): Promise<void> {
+	await page.goto("/__debug/store");
+	await expect(page.getByTestId("debug-store-ready")).toBeVisible();
+	await page.waitForFunction(() => window.__galaxyDebug?.ready === true);
+	await page.evaluate(async () => {
+		await window.__galaxyDebug!.loadSession();
+		await window.__galaxyDebug!.setDeviceSessionId(
+			"phase-19-synthetic-session",
+		);
+	});
+}
 
 const SYNTHETIC_REPORT_FIXTURE = {
 	turn: 39,
@@ -111,6 +139,7 @@ const SYNTHETIC_REPORT_FIXTURE = {
 test("synthetic-report loader navigates from lobby to map and renders", async ({
 	page,
 }) => {
+	await seedSession(page);
 	await page.goto("/lobby");
 	await expect(page.getByTestId("lobby-synthetic-section")).toBeVisible();