Add payment routes scaffold

Author: lippytm

backend/app/routes/payments.py

@@ -0,0 +1,58 @@
+from fastapi import APIRouter, HTTPException
+from pydantic import BaseModel, Field
+from typing import Optional
+from uuid import uuid4
+
+router = APIRouter(prefix="/api/payments", tags=["payments"])
+
+
+class CheckoutRequest(BaseModel):
+    product_code: str = Field(..., description="Internal product or service identifier")
+    customer_reference: str = Field(..., description="User, account, or lead identifier")
+    amount_usd: float = Field(..., gt=0)
+    currency: str = Field(default="USD")
+    mode: str = Field(default="one_time", description="one_time, subscription, or usage")
+    wallet_address: Optional[str] = None
+    metadata: dict = Field(default_factory=dict)
+
+
+class CheckoutResponse(BaseModel):
+    checkout_id: str
+    status: str
+    payment_url: Optional[str] = None
+    service_receipt_id: Optional[str] = None
+
+
+class ServiceReceiptResponse(BaseModel):
+    receipt_id: str
+    status: str
+    product_code: str
+    customer_reference: str
+    delivery_state: str
+
+
+@router.post("/checkout", response_model=CheckoutResponse)
+def create_checkout(request: CheckoutRequest) -> CheckoutResponse:
+    checkout_id = f"chk_{uuid4().hex}"
+    receipt_id = f"srv_{uuid4().hex}"
+
+    return CheckoutResponse(
+        checkout_id=checkout_id,
+        status="created",
+        payment_url=f"https://payments.example/checkout/{checkout_id}",
+        service_receipt_id=receipt_id,
+    )
+
+
+@router.get("/service-receipts/{receipt_id}", response_model=ServiceReceiptResponse)
+def get_service_receipt(receipt_id: str) -> ServiceReceiptResponse:
+    if not receipt_id.startswith("srv_"):
+        raise HTTPException(status_code=404, detail="Service receipt not found")
+
+    return ServiceReceiptResponse(
+        receipt_id=receipt_id,
+        status="active",
+        product_code="unknown",
+        customer_reference="unknown",
+        delivery_state="pending",
+    )