feat: multi-mint health tracker, discovery, portal, multi-wallet (Phase 3-8)

- mint_health.h/c: FreeRTOS probing task, GET /v1/info every 5min,
  recovery threshold 3, immediate failure, mutex-protected state
- cashu.c: health-gated acceptance (config match AND reachable)
- tollgate_api.c: one price_per_step tag per reachable mint in discovery
- captive_portal.c: mint list with green/grey indicators, /mints API,
  auto-refresh every 30s via JS
- nucula_wallet.h/cpp: multi-wallet (up to 4), route receive to correct
  wallet by mint URL, balance sums across all wallets
- tollgate_main.c: init health tracker + multi-wallet on service start
- CMakeLists.txt: add mint_health.c

1 files changed, 11 insertions, 1 deletions

diff --git a/main/tollgate_main.c b/main/tollgate_main.c
index c0ff65f..5f3e0e1 100644
--- a/main/tollgate_main.c
+++ b/main/tollgate_main.c
@@ -22,6 +22,7 @@
 #include "wifistr.h"
 #include "tollgate_client.h"
 #include "lightning_payout.h"
+#include "mint_health.h"
 #include "cvm_server.h"
 #include "display.h"
 
@@ -151,7 +152,15 @@ static void start_services(void)
     session_manager_init();
 
     const tollgate_config_t *cfg = tollgate_config_get();
-    nucula_wallet_init(cfg->mint_url);
+
+    mint_health_init(cfg->accepted_mints, cfg->accepted_mint_count);
+    mint_health_start();
+
+    if (cfg->accepted_mint_count > 1) {
+        nucula_wallet_init_multi(cfg->accepted_mints, cfg->accepted_mint_count);
+    } else {
+        nucula_wallet_init(cfg->mint_url);
+    }
     lightning_payout_init(&cfg->payout);
 
     dns_server_start(ap_ip_info.ip, upstream_dns);
@@ -187,6 +196,7 @@ static void stop_services(void)
     captive_portal_stop();
     tollgate_api_stop();
     dns_server_stop();
+    mint_health_stop();
     cvm_server_stop();
     firewall_revoke_all();
     s_services_running = false;