Add Sentry, Pino logs, and OTel spans on WS pipeline (M2).

Capture REST/WS/SSE errors in Sentry, emit structured pino logs with correlation IDs, and trace the book-tick pipeline to Sentry via OpenTelemetry.

Co-authored-by: Cursor <cursoragent@cursor.com>

e2e/smoke.spec.ts

@@ -0,0 +1,19 @@
+import { test, expect } from "@playwright/test";
+
+test("dashboard loads", async ({ page }) => {
+  await page.goto("/");
+  await expect(page.getByRole("heading", { name: /ArbPulse/i })).toBeVisible();
+});
+
+test("SSE stream connects and delivers engine state", async ({ page, request }) => {
+  const health = await request.get("/api/health");
+  expect(health.ok()).toBeTruthy();
+
+  await page.goto("/");
+  await expect(page.getByText("Connecting to engine…")).toBeHidden({
+    timeout: 45_000,
+  });
+  await expect(page.getByText("LIVE", { exact: true })).toBeVisible();
+  await expect(page.getByText("RUNNING")).toBeVisible();
+  await expect(page.getByText("Realized P&L")).toBeVisible();
+});