fix: populate lnurl/lnurl_url in nostr-transport handlers (#1)

The HTTP views populate `link.lnurl` and `link.lnurl_url` from
`request.url_for(...)`; the nostr-transport RPC handlers had no
`Request` and so left both fields as `None`. Consumers (ATMs over
nostr) were forced to provision a separate `LNBITS_HTTP_URL` env var
and compose the LNURL callback themselves.

Add `helpers.create_lnurl_from_baseurl(link)` that mirrors
`create_lnurl` but composes the callback URL from
`settings.lnbits_baseurl` instead, and thread it through the
create/get/update/list RPC handlers via a `_populate_lnurl` shim
so the response shape matches the HTTP path. Encoding errors are
swallowed (fields stay `None`) so a misconfigured baseurl falls
back to current behavior rather than failing the RPC.

Closes #1.

helpers.py

@@ -1,4 +1,5 @@
 from fastapi import Request
+from lnbits.settings import settings
 from lnurl import Lnurl
 from lnurl import encode as lnurl_encode
 from shortuuid import uuid
@@ -26,3 +27,28 @@ def create_lnurl(link: WithdrawLink, req: Request) -> Lnurl:
             f"Error creating LNURL with url: `{url!s}`, "
             "check your webserver proxy configuration."
         ) from e
+
+
+def create_lnurl_from_baseurl(link: WithdrawLink) -> Lnurl:
+    """
+    Same shape as `create_lnurl`, but composes the callback URL from
+    `settings.lnbits_baseurl` instead of a FastAPI `Request`. Used by
+    the nostr-transport RPC handlers, which have no HTTP request to
+    derive a base URL from.
+    """
+    base = settings.lnbits_baseurl.rstrip("/")
+    if link.is_unique:
+        usescssv = link.usescsv.split(",")
+        tohash = link.id + link.unique_hash + usescssv[link.number]
+        multihash = uuid(name=tohash)
+        url = f"{base}/withdraw/api/v1/lnurl/{link.unique_hash}/{multihash}"
+    else:
+        url = f"{base}/withdraw/api/v1/lnurl/{link.unique_hash}"
+
+    try:
+        return lnurl_encode(url)
+    except Exception as e:
+        raise ValueError(
+            f"Error creating LNURL with url: `{url!s}`, "
+            "check your `LNBITS_BASEURL` configuration."
+        ) from e