feat(payment): support user-bound seven-discount offers

src/data/services/api/__tests__/payment_api.test.ts

@@ -81,4 +81,38 @@ describe("PaymentApi", () => {
     });
     expect(response.message).toBe("Thank you for the thoughtful gift.");
   });
+
+  it("accepts a server-issued offer before opening the subscription page", async () => {
+    httpClientMock.mockResolvedValue({
+      success: true,
+      data: {
+        commercialOfferId: "offer-1",
+        planId: "vip_annual",
+        subscriptionType: "vip",
+        discountPercent: 30,
+        pricePercent: 70,
+        expiresAt: "2026-07-24T08:00:00+00:00",
+        message: "I got it for you.",
+        promotionType: "commercial_seven_discount",
+      },
+    });
+
+    const response = await new PaymentApi().acceptCommercialOffer("offer-1");
+
+    expect(httpClientMock).toHaveBeenCalledWith(
+      "/api/payment/commercial-offers/offer-1/accept",
+      { method: "POST" },
+    );
+    expect(response.discountPercent).toBe(30);
+  });
+
+  it("requests an offer-scoped plan catalog without changing the public call", async () => {
+    httpClientMock.mockResolvedValue({ success: true, data: { plans: [] } });
+
+    await new PaymentApi().getPlans("offer-1");
+
+    expect(httpClientMock).toHaveBeenCalledWith("/api/payment/plans", {
+      query: { commercialOfferId: "offer-1" },
+    });
+  });
 });