Phase 2 WIP: Cashu payment endpoints, session tracking, updated checklist

- Add cashu.c/h: Cashu token decode (cashuA/base64url), proof state check via mint API, allotment calculator
- Add session.c/h: time-based session management with allotment/expiry, spent secret tracking
- Add tollgate_api.c/h: HTTP server on :2121 with GET / (kind=10021 discovery), POST / (payment processing), /usage, /whoami
- Update captive portal HTML: replace Grant Free Access with Cashu token paste form + Pay & Connect button
- Update tollgate_main.c: wire in session manager, TollGate API, 1s session tick loop
- Add tests/phase2.mjs: Phase 2 test suite (discovery, invalid token, wrong mint, valid payment)
- Update CHECKLIST.md: reflect Phase 1 complete, Phase 2 in progress with known bugs

Known issues (not yet flashed):
- Stack overflow crash in httpd POST handler (need stack_size=16384 + heap allocations)
- cashu_decode_token uses 2KB stack buffer (needs heap alloc)
- Mint URL should be testnut.cashu.space (nofee.testnut has API compat issues)

1 files changed, 10 insertions, 0 deletions

diff --git a/main/tollgate_main.c b/main/tollgate_main.c
index 9eba61f..04f64b9 100644
--- a/main/tollgate_main.c
+++ b/main/tollgate_main.c
@@ -14,6 +14,8 @@
 #include "dns_server.h"
 #include "captive_portal.h"
 #include "firewall.h"
+#include "session.h"
+#include "tollgate_api.h"
 
 #define MAX_STA_RETRY 5
 #define AP_IP_ADDR "192.168.4.1"
@@ -105,9 +107,11 @@ static void start_services(void)
     upstream_dns.addr = dns_addr->addr;
 
     firewall_init(ap_ip_info.ip);
+    session_manager_init();
 
     dns_server_start(ap_ip_info.ip, upstream_dns);
     captive_portal_start();
+    tollgate_api_start();
 
     s_services_running = true;
     if (s_services_mutex) xSemaphoreGive(s_services_mutex);
@@ -123,6 +127,7 @@ static void stop_services(void)
     }
 
     captive_portal_stop();
+    tollgate_api_stop();
     dns_server_stop();
     firewall_disable_nat();
     firewall_revoke_all();
@@ -218,4 +223,9 @@ void app_main(void)
     ESP_ERROR_CHECK(esp_wifi_start());
 
     ESP_LOGI(TAG, "WiFi AP+STA started, waiting for connection...");
+
+    while (1) {
+        vTaskDelay(pdMS_TO_TICKS(1000));
+        session_tick();
+    }
 }