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>

transport_rpcs.py

@@ -20,6 +20,10 @@ link_id:...})` enforce ownership without core importing this module.
 
 from __future__ import annotations
 
+from shortuuid import uuid
+
+from lnbits.core.crud.wallets import get_wallets
+from lnbits.core.models import Account
 from lnbits.core.models.wallets import WalletTypeInfo
 from lnbits.core.services.nostr_transport.models import NostrRpcRequest
 
@@ -27,6 +31,7 @@ from .crud import (
     create_withdraw_link,
     delete_withdraw_link,
     get_withdraw_link,
+    get_withdraw_links,
     update_withdraw_link,
 )
 from .models import CreateWithdrawData
@@ -84,6 +89,92 @@ async def handle_lnurlw_delete_link(
     return {"ok": True}
 
 
+async def handle_lnurlw_list_links(
+    auth: Account, request: NostrRpcRequest
+) -> dict:
+    """List withdraw links across all wallets owned by the calling account.
+    Useful for ATMs to re-discover their links after a reconnect.
+
+    Body fields:
+      - limit: int (0 means no limit; default 0)
+      - offset: int (default 0)
+    If `request.wallet_id` is set and is one of the caller's wallets,
+    narrow to just that wallet.
+    """
+    body = request.body or {}
+    limit = int(body.get("limit") or 0)
+    offset = int(body.get("offset") or 0)
+
+    wallets = await get_wallets(auth.id)
+    wallet_ids = [w.id for w in wallets]
+    if not wallet_ids:
+        return {"data": [], "total": 0}
+    if request.wallet_id and request.wallet_id in wallet_ids:
+        wallet_ids = [request.wallet_id]
+
+    page = await get_withdraw_links(wallet_ids, limit, offset)
+    return {
+        "data": [_to_dict(link) for link in page.data],
+        "total": page.total,
+    }
+
+
+async def handle_lnurlw_unique_hashes(
+    auth: WalletTypeInfo, request: NostrRpcRequest
+) -> dict:
+    """
+    For a `is_unique=True` link, return the per-use `id_unique_hash`
+    values that the ATM uses to generate distinct QR codes — one per
+    unredeemed slot. Mirrors the formula in `helpers.py:create_lnurl`
+    exactly so an ATM never has to re-implement the derivation:
+
+        id_unique_hash = shortuuid.uuid(name=link.id + link.unique_hash + index)
+
+    `link.usescsv` is the canonical list of *unredeemed* slot indexes;
+    after a customer claims a slot it gets removed there (see
+    `crud.remove_unique_withdraw_link`). The hashes returned here are
+    therefore exactly the ones still claimable.
+
+    Response:
+      {
+        "link_id": str,
+        "unique_hash": str,            # base hash
+        "is_unique": bool,
+        "unredeemed_hashes": [         # one entry per remaining slot
+          {"index": str, "id_unique_hash": str}, ...
+        ]
+      }
+
+    For `is_unique=False` links the list is empty and `unique_hash`
+    alone identifies the callback path
+    (`/withdraw/api/v1/lnurl/<unique_hash>`). For `is_unique=True`
+    each callback path is
+    `/withdraw/api/v1/lnurl/<unique_hash>/<id_unique_hash>`.
+    """
+    link_id = _require_id(request)
+    link = await _require_owned_link(link_id, auth.wallet.id)
+
+    unredeemed = []
+    if link.is_unique:
+        # usescsv is comma-separated; split and skip empties (after the
+        # last slot is consumed it becomes the empty string).
+        for index_str in [s for s in link.usescsv.split(",") if s.strip()]:
+            tohash = link.id + link.unique_hash + index_str
+            unredeemed.append(
+                {
+                    "index": index_str.strip(),
+                    "id_unique_hash": uuid(name=tohash),
+                }
+            )
+
+    return {
+        "link_id": link.id,
+        "unique_hash": link.unique_hash,
+        "is_unique": link.is_unique,
+        "unredeemed_hashes": unredeemed,
+    }
+
+
 async def resolve_withdraw_owner(link_id: str) -> str | None:
     """For the core subscription module: link_id -> wallet_id (or None)."""
     link = await get_withdraw_link(link_id)