feat: implement atomic signup trial claims and referral discount logic with Supabase database schema updates

frontend/app/auth/callback/route.ts

@@ -1,7 +1,10 @@
 import { NextRequest, NextResponse } from "next/server";
+import { BACKEND_ENTITLEMENT_HEADER } from "@/lib/backend-auth";
 import { createSupabaseRouteClient, hasSupabaseServerEnv } from "@/lib/supabase/server";
 import { getConfiguredSiteUrl } from "@/lib/site-url";
 
+const API_BASE = process.env.POLYWEATHER_API_BASE_URL;
+
 function normalizeNextPath(input: string | null) {
   const fallback = "/";
   const raw = String(input || "").trim();
@@ -11,6 +14,34 @@ function normalizeNextPath(input: string | null) {
   return raw;
 }
 
+async function warmSignupTrial(accessToken: string) {
+  const token = String(accessToken || "").trim();
+  if (!API_BASE || !token) return;
+
+  const headers = new Headers({
+    Accept: "application/json",
+    Authorization: `Bearer ${token}`,
+  });
+  const backendToken = process.env.POLYWEATHER_BACKEND_ENTITLEMENT_TOKEN?.trim();
+  if (backendToken) {
+    headers.set(BACKEND_ENTITLEMENT_HEADER, backendToken);
+  }
+
+  const controller = new AbortController();
+  const timeoutId = setTimeout(() => controller.abort(), 2500);
+  try {
+    await fetch(`${API_BASE}/api/auth/me`, {
+      cache: "no-store",
+      headers,
+      signal: controller.signal,
+    });
+  } catch {
+    // The account/terminal bootstrap will retry. Callback must not strand login.
+  } finally {
+    clearTimeout(timeoutId);
+  }
+}
+
 export async function GET(request: NextRequest) {
   const siteUrl = getConfiguredSiteUrl();
   if (siteUrl) {
@@ -38,7 +69,10 @@ export async function GET(request: NextRequest) {
   const supabase = createSupabaseRouteClient(request, response);
   const code = request.nextUrl.searchParams.get("code");
   if (code) {
-    await supabase.auth.exchangeCodeForSession(code);
+    const {
+      data: { session },
+    } = await supabase.auth.exchangeCodeForSession(code);
+    await warmSignupTrial(session?.access_token || "");
   }
 
   return response;