Phase 5: Lightning auto-payout with LNURL-pay and NUT-05 melt

- New lnurl_pay.c/h: LNURL-pay protocol (GET .well-known/lnurlp + callback)
- New lightning_payout.c/h: threshold-based auto-payout with multi-recipient split
- Extended nucula_wallet bridge with nucula_wallet_melt() (NUT-05)
- Config: payout section with multi-mint, multi-recipient, fee_tolerance
- Default: enabled, TollGate@coinos.io, min_payout=128, min_balance=64
- 18 new unit tests (all passing), 134 total

1 files changed, 37 insertions, 0 deletions

diff --git a/main/lightning_payout.h b/main/lightning_payout.h
new file mode 100644
index 0000000..d353902
--- /dev/null
+++ b/main/lightning_payout.h
@@ -0,0 +1,37 @@
+#ifndef LIGHTNING_PAYOUT_H
+#define LIGHTNING_PAYOUT_H
+
+#include "esp_err.h"
+#include <stdint.h>
+#include <stdbool.h>
+
+#define PAYOUT_MAX_RECIPIENTS     4
+#define PAYOUT_MAX_MINTS          3
+#define PAYOUT_MAX_ADDR_LEN       128
+
+typedef struct {
+    char lightning_address[PAYOUT_MAX_ADDR_LEN];
+    double factor;
+} payout_recipient_t;
+
+typedef struct {
+    char url[256];
+    uint64_t min_balance;
+    uint64_t min_payout_amount;
+} payout_mint_config_t;
+
+typedef struct {
+    bool enabled;
+    payout_mint_config_t mints[PAYOUT_MAX_MINTS];
+    int mint_count;
+    payout_recipient_t recipients[PAYOUT_MAX_RECIPIENTS];
+    int recipient_count;
+    uint64_t fee_tolerance_pct;
+    int check_interval_s;
+} payout_config_t;
+
+esp_err_t lightning_payout_init(const payout_config_t *config);
+
+void lightning_payout_tick(void);
+
+#endif