feat: lnurlw_list_links + lnurlw_unique_hashes transport RPCs

Two additions surface withdraw-extension capabilities the ATM use
case in aiolabs/lamassu-next (issues #24, #25) needs but couldn't
reach over the nostr transport before:

## lnurlw_list_links (AUTH_ACCOUNT)

Enumerate withdraw links across all wallets owned by the calling
account, with `limit`/`offset` pagination matching the existing
HTTP `/api/v1/links`. Lets an ATM (or any client) re-discover its
links after a reconnect without having to keep its own index.

If `request.wallet_id` is supplied and matches one of the account's
wallets, narrows the listing to just that wallet — mirrors lnurlp's
list semantics.

Returns `{data: [...links], total: <int>}`.

## lnurlw_unique_hashes (AUTH_WALLET)

For an `is_unique=True` link, return the per-use `id_unique_hash`
values derived from each unredeemed slot in `link.usescsv`. Mirrors
the formula in `helpers.py:create_lnurl:13`:

  id_unique_hash = shortuuid.uuid(name=link.id + link.unique_hash + index)

Without this RPC an ATM that wants to generate distinct QR codes
per use (lamassu-next #25) had to reimplement the derivation
client-side — fragile if the extension's hash format ever changes
upstream. With this RPC the ATM asks the server for the canonical
list of unredeemed hashes; each one becomes the trailing path
component of `/withdraw/api/v1/lnurl/<unique_hash>/<id_unique_hash>`.

`is_unique=False` links return an empty `unredeemed_hashes` list;
the base `unique_hash` alone identifies the callback path.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

__init__.py

@@ -33,6 +33,7 @@ def withdraw_start() -> None:
     """
     try:
         from lnbits.core.services.nostr_transport.dispatcher import (
+            AUTH_ACCOUNT,
             AUTH_WALLET,
             register_rpc,
         )
@@ -46,12 +47,16 @@ def withdraw_start() -> None:
         handle_lnurlw_create_link,
         handle_lnurlw_delete_link,
         handle_lnurlw_get_link,
+        handle_lnurlw_list_links,
+        handle_lnurlw_unique_hashes,
         handle_lnurlw_update_link,
         resolve_withdraw_owner,
     )
 
     register_rpc("lnurlw_create_link", handle_lnurlw_create_link, AUTH_WALLET)
     register_rpc("lnurlw_get_link", handle_lnurlw_get_link, AUTH_WALLET)
+    register_rpc("lnurlw_list_links", handle_lnurlw_list_links, AUTH_ACCOUNT)
+    register_rpc("lnurlw_unique_hashes", handle_lnurlw_unique_hashes, AUTH_WALLET)
     register_rpc("lnurlw_update_link", handle_lnurlw_update_link, AUTH_WALLET)
     register_rpc("lnurlw_delete_link", handle_lnurlw_delete_link, AUTH_WALLET)
     register_link_owner_resolver(