Unique SSID/IP per board + captive detection fix + mint list in portal

- Derive unique SSID (TollGate-{MAC4}{MAC5}) and AP IP (10.{b5}.{subnet}.1)
  from factory MAC — boards no longer conflict
- Board A: TollGate-377C @ 10.55.85.1, Board B: TollGate-5050 @ 10.80.10.1
- Captive portal detection URIs return 200 with portal HTML (matching
  esp32-mesh working approach) instead of 302 redirect
- Dynamic AP IP in portal HTML via __AP_IP__ template substitution
- Supported mints section in portal page (shows mint URL, tap to copy)
- Fixed mint URL to testnut.cashu.space (was stale in SPIFFS)
- DoT reject server on port 853 for DNS-over-TLS fallback
- DNS hijack: NXDOMAIN for all non-A queries, no forwarding for unauthed
- Playwright tests updated for 200 response on detection URIs
- Phase 2 test suite: 20/21 pass (test 22 expiry ping route issue)
- Tests 25-27 deferred to Phase 3 (Board B as second client)

1 files changed, 9 insertions, 0 deletions

diff --git a/main/config.h b/main/config.h
index d26b7ae..dd3fe05 100644
--- a/main/config.h
+++ b/main/config.h
@@ -3,6 +3,8 @@
 
 #include "esp_err.h"
 #include "esp_wifi.h"
+#include "esp_netif.h"
+#include <stdbool.h>
 
 #define TOLLGATE_MAX_WIFI_NETWORKS 5
 #define TOLLGATE_MAX_MINT_URLS     3
@@ -25,12 +27,19 @@ typedef struct {
     uint8_t ap_channel;
     uint8_t ap_max_conn;
 
+    esp_ip4_addr_t ap_ip;
+    char ap_ip_str[16];
+
     char mint_url[256];
     char lnurl_url[256];
     int price_per_step;
     int step_size_ms;
+
+    bool unique_derived;
 } tollgate_config_t;
 
+void tollgate_config_derive_unique(tollgate_config_t *cfg);
+
 esp_err_t tollgate_config_init(void);
 const tollgate_config_t *tollgate_config_get(void);
 esp_err_t tollgate_config_get_wifi(wifi_config_t *wifi_config);