feat(web): add Next.js portfolio with live MT5 dashboard

- Linear design system (dark canvas, lavender accent)
- Live account stats, open positions, pending orders (30s polling)
- Trade history with equity curve chart
- Backtest results table
- Proxy API routes — MT5_BASE_URL server-side only, never exposed to browser
- Deploy on Vercel: set MT5_BASE_URL env var

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/components/Nav.tsx

@@ -0,0 +1,48 @@
+"use client";
+import Link from "next/link";
+import { usePathname } from "next/navigation";
+import clsx from "clsx";
+
+const links = [
+  { href: "/",         label: "Dashboard" },
+  { href: "/trades",   label: "Trades"    },
+  { href: "/backtest", label: "Backtest"  },
+];
+
+export default function Nav() {
+  const path = usePathname();
+  return (
+    <nav className="sticky top-0 z-50" style={{ backgroundColor: 'var(--c-canvas)', borderBottom: '1px solid var(--c-hl)' }}>
+      <div className="max-w-5xl mx-auto px-4 sm:px-6 h-14 flex items-center gap-6">
+        {/* wordmark */}
+        <Link href="/" className="font-mono text-xs tracking-widest text-ink-sub uppercase hover:text-ink transition-colors">
+          ARES
+        </Link>
+
+        {/* nav links */}
+        <div className="flex gap-1">
+          {links.map(({ href, label }) => (
+            <Link
+              key={href}
+              href={href}
+              className={clsx(
+                "px-3 py-1.5 rounded-md text-sm transition-colors",
+                path === href
+                  ? "bg-s2 text-ink"
+                  : "text-ink-sub hover:text-ink hover:bg-s1"
+              )}
+            >
+              {label}
+            </Link>
+          ))}
+        </div>
+
+        {/* live indicator */}
+        <div className="ml-auto flex items-center gap-2">
+          <span className="w-1.5 h-1.5 rounded-full bg-bull pulse-dot" />
+          <span className="text-xs text-ink-sub font-medium tracking-eyebrow uppercase">Live</span>
+        </div>
+      </div>
+    </nav>
+  );
+}