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, 1 insertions, 0 deletions

diff --git a/components/nucula_lib/nucula_wallet.h b/components/nucula_lib/nucula_wallet.h
index 784a126..3c1f3f8 100644
--- a/components/nucula_lib/nucula_wallet.h
+++ b/components/nucula_lib/nucula_wallet.h
@@ -9,6 +9,7 @@ extern "C" {
 #endif
 
 esp_err_t nucula_wallet_init(const char *mint_url);
+esp_err_t nucula_wallet_init_multi(const char mint_urls[][256], int count);
 
 esp_err_t nucula_wallet_receive(const char *token_str);