fix: use correct Lightning.Pub pubkey and pointer in ndebit generation

The ndebit must encode Lightning.Pub's pubkey (not the ATM's pubkey)
so that Kind 21002 debit requests are received by Lightning.Pub.

Also added the 'atm' pointer to identify which Lightning.Pub user
account should pay the invoice.

Fixes:
- Changed pubkey from ATM identity to Lightning.Pub pubkey
- Added pointer: 'atm' to ndebit encoding
- Updated hardcoded pubkey to match current Lightning.Pub instance

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lamassu-next/apps/machine/src/services/lightning.ts

@@ -40,7 +40,7 @@ const LOCAL_IP = '192.168.1.122' // Change this to your machine's local IP
 
 const DEV_CONFIG = {
   // Lightning.Pub Nostr pubkey (from docker logs - check with: docker logs lamassu-lightning-pub | grep pubkey)
-  lightningPubPubkey: 'f454c5eec4ec4474128e19b57b45e49c3d0851d01eea960b39ce391cdba76fc6',
+  lightningPubPubkey: '4be8e203a3341bb2b74a4dcbf8774e061437f63ec21af7ec3144c8d0a68e2f39',
   // Local strfry relay - use local IP for cross-device testing
   relayUrl: `ws://${LOCAL_IP}:7777`,
   // Admin token for HTTP API (development only)
@@ -202,10 +202,14 @@ function createATMServices(
     generateNdebit: async (context: ATMContext): Promise<string> => {
       console.log('[ATM Service] Generating ndebit for', context.satsAmount, 'sats')
 
-      // Create ndebit with ATM's pubkey and relay
+      // Create ndebit with Lightning.Pub's pubkey (not ATM's pubkey!)
+      // The wallet sends Kind 21002 to the pubkey in the ndebit,
+      // so it must be Lightning.Pub's pubkey for it to receive and pay.
+      // The pointer identifies which Lightning.Pub user account pays (e.g., "atm")
       const ndebit = encodeNdebit({
-        pubkey: _identity.publicKey,
+        pubkey: DEV_CONFIG.lightningPubPubkey,
         relay: DEV_CONFIG.relayUrl,
+        pointer: 'atm', // Lightning.Pub user identifier for the ATM account
       })
 
       // Format as full URI with amount