test(ui): migrate suite to the app-shell (state-driven navigation)

- Unit: repoint moved screen imports (lib/screens, lib/game), mock
  $lib/app-nav (appScreen/activeView) instead of $app/navigation, drop the
  removed gameId props, assert screen/view selection.
- e2e: add a dev-only window.__galaxyNav affordance; specs enter a game via
  enterGame(...) instead of a /games/:id URL; URL assertions become content
  assertions (the URL stays /game/); reload uses waitUntil:"commit" (shallow
  routing) and mocks /rpc on game entry.
- Remove the obsolete report scroll-restore test (it relied on a SvelteKit
  route Snapshot that no longer exists); update the missing-membership test
  to the new lobby-redirect+toast behaviour. Fix a stale report.svelte
  docstring.

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

ui/frontend/tests/e2e/cargo-routes.spec.ts

@@ -378,7 +378,12 @@ test("cargo-routes flow: pick a destination, arrow appears, reload restores", as
 
 	const handle = await mockGateway(page);
 	await bootSession(page);
-	await page.goto(`/games/${GAME_ID}/map`);
+	await page.goto("/");
+	await page.waitForFunction(() => window.__galaxyNav !== undefined);
+	await page.evaluate(
+		(id) => window.__galaxyNav!.enterGame(id, "map", {}),
+		GAME_ID,
+	);
 	await expect(page.getByTestId("active-view-map")).toHaveAttribute(
 		"data-status",
 		"ready",