Add Polaris frontend: storefront + admin console (React 18/Vite/TS/Tailwind)

- Shared src/lib/api.ts fetch wrapper -> /api with Cache-Control: no-store
- Storefront: home hero, shop grid (category filter + search), product detail,
  cart, checkout (POST /api/orders -> confirmation + order number), order tracking
- Admin: JWT login, today KPI dashboard (revenue/orders/gross/net/margin/aov/refunds),
  top products, supplier performance, product import, lifecycle view, order list
  with tracking simulation
- Multi-stage Dockerfile (Vite build -> nginx static + /api proxy -> api:8000)
- nginx.conf with SPA fallback and no-store HTML caching
- mock/mock_api.py for local verification (excluded from image)

frontend/src/components/StoreLayout.tsx

@@ -0,0 +1,84 @@
+import { Link, NavLink, Outlet } from 'react-router-dom';
+import { useCart } from '../store/cart';
+import { IconCart, IconCoffee, IconExternalLink, IconStar, IconTruck } from './Icons';
+
+const navLink = ({ isActive }: { isActive: boolean }) =>
+  `rounded-lg px-3 py-2 text-sm font-medium transition ${
+    isActive ? 'bg-white/[0.08] text-white' : 'text-slate-400 hover:text-white'
+  }`;
+
+export default function StoreLayout() {
+  const { count } = useCart();
+
+  return (
+    <div className="bg-app flex min-h-screen flex-col">
+      <header className="sticky top-0 z-40 border-b border-white/[0.06] bg-night-950/70 backdrop-blur-xl">
+        <div className="mx-auto flex h-16 max-w-7xl items-center justify-between px-4 sm:px-6">
+          <Link to="/" className="flex items-center gap-2.5">
+            <span className="flex h-9 w-9 items-center justify-center rounded-xl bg-gradient-to-br from-indigo-500 to-violet-600 shadow-glow">
+              <IconStar className="h-5 w-5 text-white" />
+            </span>
+            <span className="text-lg font-bold tracking-tight text-white">
+              Polaris<span className="text-indigo-400">.</span>
+            </span>
+          </Link>
+
+          <nav className="hidden items-center gap-1 md:flex">
+            <NavLink to="/" end className={navLink}>
+              Home
+            </NavLink>
+            <NavLink to="/shop" className={navLink}>
+              Shop
+            </NavLink>
+            <NavLink to="/track" className={navLink}>
+              Track order
+            </NavLink>
+          </nav>
+
+          <div className="flex items-center gap-2">
+            <Link to="/track" className="btn-ghost !px-3 !py-2 md:hidden" title="Track order">
+              <IconTruck className="h-4 w-4" />
+            </Link>
+            <Link to="/cart" className="btn-ghost relative !px-3.5 !py-2">
+              <IconCart className="h-4 w-4" />
+              <span className="hidden sm:inline">Cart</span>
+              {count > 0 && (
+                <span className="absolute -right-1.5 -top-1.5 flex h-5 min-w-[1.25rem] items-center justify-center rounded-full bg-gradient-to-r from-indigo-500 to-violet-500 px-1 text-[11px] font-bold text-white shadow-glow">
+                  {count}
+                </span>
+              )}
+            </Link>
+          </div>
+        </div>
+      </header>
+
+      <main className="flex-1">
+        <Outlet />
+      </main>
+
+      <footer className="border-t border-white/[0.06] bg-night-900/60">
+        <div className="mx-auto flex max-w-7xl flex-col items-center justify-between gap-4 px-4 py-8 sm:flex-row sm:px-6">
+          <div className="flex items-center gap-2 text-sm text-slate-400">
+            <IconStar className="h-4 w-4 text-indigo-400" />
+            <span>Polaris — automated commerce, by starlight.</span>
+          </div>
+          <div className="flex items-center gap-4 text-sm">
+            <Link to="/admin" className="text-slate-500 transition hover:text-indigo-300">
+              Admin
+            </Link>
+            <a
+              href="https://buymeacoffee.com/r26xrthzttg"
+              target="_blank"
+              rel="noopener noreferrer"
+              className="inline-flex items-center gap-1.5 rounded-lg border border-white/10 bg-white/[0.04] px-3 py-1.5 text-amber-200/90 transition hover:bg-white/[0.08]"
+            >
+              <IconCoffee className="h-4 w-4" />
+              Buy me a coffee
+              <IconExternalLink className="h-3.5 w-3.5 opacity-60" />
+            </a>
+          </div>
+        </div>
+      </footer>
+    </div>
+  );
+}