slice 1g: Next.js M1 overview panel + Primary-Rule lint (ADR-0007)

Symbol command bar (Zustand active-symbol) -> OverviewPanel (price + day-change
shape/color/label per P7 G3 + Recharts sparkline + sector) + signup/login + ADR-0007
footer. next.config rewrites proxy /api -> backend:3001 (same-origin cookies). Vanilla
fetch tRPC client (decoupled from server Node types). Primary-Rule lint 2/2 green.
Slice 1 tracer bullet COMPLETE: 38 tests green, live-verified end-to-end.

app/next.config.ts

@@ -0,0 +1,11 @@
+import type { NextConfig } from "next";
+
+// Proxy /api/* to the local Bun/Node backend (slice 1f) so the SPA and backend share an
+// origin — session cookies work without cross-origin/CORS gymnastics (DESIGN.md §2.1).
+const nextConfig: NextConfig = {
+  rewrites: async () => [
+    { source: "/api/:path*", destination: "http://localhost:3001/api/:path*" },
+  ],
+};
+
+export default nextConfig;