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

app/(chat)/api/chat/route.ts

@@ -5,8 +5,7 @@ import {
   stepCountIs,
   streamText,
 } from "ai";
-import { auth, type UserType } from "@/app/(auth)/auth";
-import { entitlementsByUserType } from "@/lib/ai/entitlements";
+import { auth } from "@/app/(auth)/auth";
 import {
   allowedModelIds,
   DEFAULT_CHAT_MODEL,
@@ -15,10 +14,10 @@ import {
 import { type RequestHints, systemPrompt } from "@/lib/ai/prompts";
 import { getLanguageModel } from "@/lib/ai/providers";
 import { getWeather } from "@/lib/ai/tools/get-weather";
+import { withLimit } from "@/lib/ai/tools/with-limit";
 import {
   deleteChatById,
   getChatById,
-  getMessageCountByUserId,
   getMessagesByChatId,
   saveChat,
   saveMessages,
@@ -28,6 +27,10 @@ import {
 import type { DBMessage } from "@/lib/db/schema";
 import { ChatbotError } from "@/lib/errors";
 import { checkIpRateLimit } from "@/lib/ratelimit";
+import {
+  checkAndConsume,
+  LimitExceededError,
+} from "@/lib/subscription/service";
 import type { ChatMessage } from "@/lib/types";
 import { convertToUIMessages, generateUUID } from "@/lib/utils";
 import { generateTitleFromUserMessage } from "../../actions";
@@ -69,19 +72,25 @@ export async function POST(request: Request) {
 
     await checkIpRateLimit(getClientIp(request));
 
-    const userType: UserType = session.user.type;
-
-    const messageCount = await getMessageCountByUserId({
-      id: session.user.id,
-      differenceInHours: 1,
-    });
-
-    if (messageCount > entitlementsByUserType[userType].maxMessagesPerHour) {
-      return new ChatbotError("rate_limit:chat").toResponse();
-    }
-
     const isToolApprovalFlow = Boolean(messages);
 
+    if (!isToolApprovalFlow) {
+      try {
+        await checkAndConsume(session.user.id, "chat_message");
+      } catch (error) {
+        if (error instanceof LimitExceededError) {
+          return Response.json(
+            {
+              code: "rate_limit:chat",
+              message: `Daily message limit reached (${error.used}/${error.limit} on ${error.tier} tier). Upgrade to Pro at /pricing.`,
+            },
+            { status: 429 }
+          );
+        }
+        throw error;
+      }
+    }
+
     const chat = await getChatById({ id });
     let messagesFromDb: DBMessage[] = [];
     let titlePromise: Promise<string> | null = null;
@@ -165,6 +174,8 @@ export async function POST(request: Request) {
 
     const modelMessages = await convertToModelMessages(uiMessages);
 
+    const meteredWeather = withLimit(getWeather, "tool_call", session.user.id);
+
     const stream = createUIMessageStream({
       originalMessages: isToolApprovalFlow ? uiMessages : undefined,
       execute: async ({ writer: dataStream }) => {
@@ -176,7 +187,7 @@ export async function POST(request: Request) {
           experimental_activeTools:
             isReasoningModel && !supportsTools ? [] : ["getWeather"],
           tools: {
-            getWeather,
+            getWeather: meteredWeather,
           },
         });