plugin: nwc: lookup_invoice: fix exc, include b11

Fixes exception in lookup_invoice:
```
 62.69 | E | plugins.nwc.nwcserver.NWCServer | Error handling nwc request
Traceback (most recent call last):
  File "/home/user/code/vibecoding_vm/electrum/electrum/plugins/nwc/nwcserver.py", line 381, in run_request_task
    await task
  File "/home/user/code/vibecoding_vm/electrum/electrum/util.py", line 1211, in wrapper
    return await func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/code/vibecoding_vm/electrum/electrum/plugins/nwc/nwcserver.py", line 526, in handle_lookup_invoice
    info = self.wallet.lnworker.get_payment_info(invoice.payment_hash, direction=RECEIVED)
                                                 ^^^^^^^^^^^^^^^^^^^^
AttributeError: 'Invoice' object has no attribute 'payment_hash'
```

Always includes bolt11 invoice in response, even if the client already
sent it to us in the request. It doesn't seem useful and is marked
optional in the spec but https://sandbox.albylabs.com considers the
response invalid if the invoice is not included.

electrum/plugins/nwc/nwcserver.py

@@ -523,7 +523,7 @@ class NWCServer(Logger, EventListener):
             b11 = invoice.lightning_invoice
         elif self.wallet.get_request(invoice.rhash):
             direction = "incoming"
-            info = self.wallet.lnworker.get_payment_info(invoice.payment_hash, direction=RECEIVED)
+            info = self.wallet.lnworker.get_payment_info(bytes.fromhex(invoice.rhash), direction=RECEIVED)
             _, b11 = self.wallet.lnworker.get_bolt11_invoice(
                 payment_info=info,
                 message=invoice.message,
@@ -539,11 +539,10 @@ class NWCServer(Logger, EventListener):
                 "created_at": invoice.time,
                 "expires_at": invoice.get_expiration_date(),
                 "fees_paid": 0,
+                "invoice": b11,
                 "metadata": {}
             }
         }
-        if payment_hash:  # if client requested by payment hash we add the invoice
-            response['result']['invoice'] = b11
         if nip47_status := self.invoice_status_to_nip47_state(status):
             response['result']['state'] = nip47_status