feat(billing): brand checkout + auto-prefill user details

#1 Checkout branding (within Razorpay's hosted-UI limits):
- image: /icons/192.png — Tia logo in the checkout header
- theme color #fb7185 (Tia rose, matches app theme-color) — was terracotta
- Note: Razorpay Checkout is their hosted UI; logo + brand color + name are
  the only customisable bits. Fonts/layout cannot be changed (platform limit).

#2 Auto-prefill name/email/phone:
- UpgradeButton now fetches /api/auth/profile on mount and passes
  prefill {name, email, contact} to Razorpay. User can still edit in checkout.
- Saves manual entry; uses the phone we now collect.

(#3 "seller doesn't support recurring payments" is a Razorpay ACCOUNT setting,
 not code — needs subscriptions enabled on the account. Handled separately.)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/UpgradeButton.tsx

@@ -8,8 +8,10 @@ interface RazorpayOptions {
   subscription_id: string;
   name: string;
   description: string;
+  image?: string; // brand logo shown in the checkout header
   handler: (resp: RazorpayResponse) => void;
-  prefill?: { email?: string; contact?: string };
+  prefill?: { name?: string; email?: string; contact?: string };
+  notes?: Record<string, string>;
   theme?: { color?: string };
   modal?: { ondismiss?: () => void };
 }
@@ -73,9 +75,19 @@ export function UpgradeButton({
   const [loading, setLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
   const [done, setDone] = useState(false);
+  // Auto-prefill from the signed-in user's profile (editable in checkout).
+  const [profile, setProfile] = useState<{ name?: string; email?: string; phone?: string }>({});
 
-  // Warm the checkout script so the first click is instant.
-  useEffect(() => { loadCheckout(); }, []);
+  // Warm the checkout script + load profile so the first click is instant.
+  useEffect(() => {
+    loadCheckout();
+    fetch("/api/auth/profile", { credentials: "include" })
+      .then((r) => r.json())
+      .then((d) => {
+        if (d.user) setProfile({ name: d.user.name, email: d.user.email, phone: d.user.phone || undefined });
+      })
+      .catch(() => {});
+  }, []);
 
   const handleUpgrade = async () => {
     setLoading(true);
@@ -91,14 +103,23 @@ export function UpgradeButton({
 
       const { subscriptionId, keyId } = createData as { subscriptionId: string; keyId: string };
 
+      // Build prefill from the explicit prop (if any) + the loaded profile.
+      // Razorpay shows these pre-filled but the user can still edit them.
+      const prefill: { name?: string; email?: string; contact?: string } = {};
+      const prefillEmail = email || profile.email;
+      if (profile.name) prefill.name = profile.name;
+      if (prefillEmail) prefill.email = prefillEmail;
+      if (profile.phone) prefill.contact = profile.phone;
+
       // 2. Open Razorpay Checkout for the mandate.
       const rzp = new window.Razorpay({
         key: keyId, // id only — never the secret
         subscription_id: subscriptionId,
         name: "Tia",
         description: "Tia Premium — ₹199/month",
-        prefill: email ? { email } : undefined,
-        theme: { color: "#C26B4E" }, // heirloom terracotta
+        image: `${window.location.origin}/icons/192.png`, // brand logo in checkout header
+        prefill: Object.keys(prefill).length ? prefill : undefined,
+        theme: { color: "#fb7185" }, // Tia rose (matches app theme-color)
         handler: async (resp) => {
           // 3. Verify for UX feedback only — entitlement comes via webhook.
           try {