Add Umami analytics, subscription tiers, tool-call metering

- Analytics: <Analytics /> in root layout loads umami when NEXT_PUBLIC_UMAMI_* env are set
- Subscription: free/pro tiers in Postgres, daily quotas (10msg/5tool free, 1000/500 pro)
- Chat route: checkAndConsume(chat_message) gate before streamText, 429 when exhausted
- Tool metering: getWeather wrapped with withLimit decorator that deducts tool_call quota
- Pricing page at /pricing with upgrade button
- /api/billing/checkout posts to EGBE payment gateway, /api/billing/webhook verifies HMAC and upgrades user on checkout.session.completed
- UsageBadge in chat header polls /api/usage every 15s
- Dropped now-unused entitlements.ts

components/analytics.tsx

@@ -0,0 +1,20 @@
+import Script from "next/script";
+
+export function Analytics() {
+  const websiteId = process.env.NEXT_PUBLIC_UMAMI_WEBSITE_ID;
+  const scriptUrl = process.env.NEXT_PUBLIC_UMAMI_SCRIPT_URL;
+
+  if (!(websiteId && scriptUrl)) {
+    return null;
+  }
+
+  return (
+    <Script
+      async
+      data-website-id={websiteId}
+      defer
+      src={scriptUrl}
+      strategy="afterInteractive"
+    />
+  );
+}

components/chat/chat-header.tsx

@@ -1,11 +1,10 @@
 "use client";
 
 import { PanelLeftIcon } from "lucide-react";
-import Link from "next/link";
 import { memo } from "react";
 import { Button } from "@/components/ui/button";
 import { useSidebar } from "@/components/ui/sidebar";
-import { VercelIcon } from "./icons";
+import { UsageBadge } from "./usage-badge";
 import { VisibilitySelector, type VisibilityType } from "./visibility-selector";
 
 function PureChatHeader({
@@ -34,15 +33,6 @@ function PureChatHeader({
         <PanelLeftIcon className="size-4" />
       </Button>
 
-      <Link
-        className="flex size-8 items-center justify-center rounded-lg md:hidden"
-        href="https://vercel.com/templates/next.js/chatbot"
-        rel="noopener noreferrer"
-        target="_blank"
-      >
-        <VercelIcon size={14} />
-      </Link>
-
       {!isReadonly && (
         <VisibilitySelector
           chatId={chatId}
@@ -50,19 +40,9 @@ function PureChatHeader({
         />
       )}
 
-      <Button
-        asChild
-        className="hidden rounded-lg bg-foreground px-4 text-background hover:bg-foreground/90 md:ml-auto md:flex"
-      >
-        <Link
-          href="https://vercel.com/templates/next.js/chatbot"
-          rel="noopener noreferrer"
-          target="_blank"
-        >
-          <VercelIcon size={16} />
-          Deploy with Vercel
-        </Link>
-      </Button>
+      <div className="ml-auto flex items-center gap-2">
+        <UsageBadge />
+      </div>
     </header>
   );
 }

components/chat/usage-badge.tsx

@@ -0,0 +1,44 @@
+"use client";
+
+import Link from "next/link";
+import useSWR from "swr";
+import type { QuotaSummary } from "@/lib/subscription/service";
+import { fetcher } from "@/lib/utils";
+
+export function UsageBadge() {
+  const { data } = useSWR<QuotaSummary>(
+    `${process.env.NEXT_PUBLIC_BASE_PATH ?? ""}/api/usage`,
+    fetcher,
+    {
+      refreshInterval: 15_000,
+      revalidateOnFocus: true,
+    }
+  );
+
+  if (!data) {
+    return null;
+  }
+
+  const isPro = data.tier === "pro";
+  const lowQuota =
+    !isPro &&
+    (data.messages.remaining <= 2 || data.toolCalls.remaining <= 1);
+
+  return (
+    <Link
+      className={`flex items-center gap-2 rounded-lg border px-2.5 py-1 text-[11px] font-medium transition-colors ${
+        lowQuota
+          ? "border-amber-500/40 bg-amber-500/10 text-amber-600 hover:bg-amber-500/15"
+          : "border-border/40 text-muted-foreground hover:text-foreground"
+      }`}
+      href="/pricing"
+      title={`${data.tier} tier — ${data.toolCalls.used}/${data.toolCalls.limit} tool calls today`}
+    >
+      <span className="uppercase tracking-wider opacity-60">{data.tier}</span>
+      <span>
+        {data.messages.used}/{data.messages.limit} msgs
+      </span>
+      {isPro ? null : <span aria-hidden>→</span>}
+    </Link>
+  );
+}

components/pricing-client.tsx

@@ -0,0 +1,48 @@
+"use client";
+
+import { useState } from "react";
+import { toast } from "sonner";
+import { Button } from "@/components/ui/button";
+import type { Tier } from "@/lib/subscription/config";
+
+export function PricingClient({ currentTier }: { currentTier: Tier }) {
+  const [loading, setLoading] = useState(false);
+
+  if (currentTier === "pro") {
+    return (
+      <p className="text-muted-foreground text-sm">
+        You're on Pro. Manage your subscription through the receipt email link.
+      </p>
+    );
+  }
+
+  const upgrade = async () => {
+    setLoading(true);
+    try {
+      const response = await fetch("/api/billing/checkout", { method: "POST" });
+      const data = await response.json();
+      if (response.ok && data.url) {
+        window.location.href = data.url;
+        return;
+      }
+      toast.error(data.message ?? "Failed to start checkout");
+    } catch (error) {
+      toast.error(error instanceof Error ? error.message : "Checkout failed");
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  return (
+    <div className="flex justify-center">
+      <Button
+        className="px-6"
+        disabled={loading}
+        onClick={upgrade}
+        size="lg"
+      >
+        {loading ? "Opening checkout..." : "Upgrade to Pro"}
+      </Button>
+    </div>
+  );
+}