fix(landing): render Trade-In nav item as external <a> to /trade-in/v2

/trade-in/** is proxied by Caddy to a separate tradein-frontend app
(basePath /trade-in, canonical /trade-in/v2). The internal <Link
href="/trade-in/"> made Next prefetch an RSC payload for a route this
app doesn't own -> Caddy returns the other app's 307 -> 'Failed to fetch
RSC payload for /trade-in' + ChunkLoadError in the console on every
landing visit. Add NavItem.external; external items render a plain <a>
(no prefetch/client-nav) pointing at the canonical /trade-in/v2. Pilot
ACL unaffected: /trade-in/v2 still matches the /trade-in/** allow glob
(test added).

frontend/src/components/landing/TopNav.tsx

@@ -23,12 +23,21 @@ import { useMe } from "@/lib/useMe";
 interface NavItem {
   href: string;
   label: string;
+  /**
+   * true → путь обслуживает ОТДЕЛЬНОЕ приложение за Caddy (не этот Next-фронт),
+   * рендерим plain `<a>` без prefetch/client-navigation. Иначе Next
+   * префетчит RSC для чужого маршрута → «Failed to fetch RSC payload» +
+   * ChunkLoadError в консоли (Caddy отдаёт 307 стороннего приложения).
+   */
+  external?: boolean;
 }
 
 const NAV_ITEMS: NavItem[] = [
   { href: "/analytics", label: "Аналитика" },
   { href: "/site-finder", label: "Site Finder" },
-  { href: "/trade-in/", label: "Trade-In" },
+  // /trade-in/** проксируется Caddy в отдельный tradein-frontend (basePath
+  // /trade-in, canonical /trade-in/v2). Для ЭТОГО приложения — внешняя ссылка.
+  { href: "/trade-in/v2", label: "Trade-In", external: true },
   { href: "/concept", label: "Концепция" },
   { href: "/admin/scrape/all", label: "Админ" },
 ];
@@ -81,19 +90,24 @@ export function TopNav({ rightSlot }: TopNavProps) {
         GenDesign
       </Link>
       <div style={{ display: "flex", gap: 24, alignItems: "center" }}>
-        {items.map((item) => (
-          <Link
-            key={item.href}
-            href={item.href}
-            style={{
-              fontSize: 14,
-              color: "var(--fg-secondary)",
-              textDecoration: "none",
-            }}
-          >
-            {item.label}
-          </Link>
-        ))}
+        {items.map((item) => {
+          const linkStyle = {
+            fontSize: 14,
+            color: "var(--fg-secondary)",
+            textDecoration: "none",
+          } as const;
+          // Внешний маршрут (за Caddy → другое приложение): plain <a>, без
+          // Next prefetch/RSC — иначе ChunkLoadError в консоли лендинга.
+          return item.external ? (
+            <a key={item.href} href={item.href} style={linkStyle}>
+              {item.label}
+            </a>
+          ) : (
+            <Link key={item.href} href={item.href} style={linkStyle}>
+              {item.label}
+            </Link>
+          );
+        })}
         {rightSlot}
       </div>
     </nav>

frontend/src/lib/__tests__/isPathAllowed.test.ts

@@ -42,6 +42,8 @@ describe("isPathAllowed — pilot allowed paths (только trade-in)", () =>
   const allowed: string[] = [
     "/trade-in",
     "/trade-in/",
+    // canonical prod-маршрут (TopNav nav-item href, обслуживается tradein-frontend)
+    "/trade-in/v2",
     "/trade-in/123",
     "/trade-in/api/v1/search",
     "/trade-in/api/v1/me",