feat(mining): integrate mining subsystem into existing modules

- CMakeLists.txt: add 6 mining sources + tcp_transport dependency
- config.h/c: mining_payout_mode_t enum, mining config fields, JSON parsing
- tollgate_main.c: mining init in start_services(), stratum_client_tick in main loop
- tollgate_api.c: GET /mining/job, POST /mining/share, GET /mining/stats endpoints
- session.h/c: payment_method_t enum (CASHU/MINING/BYTES)
- firewall.h/c: sandbox allowlist for mining port + mint URLs
- tollgate_client.h/c: TG_CLIENT_MINING state, mining discovery tag parsing
- captive_portal.c: tabbed UI with Cashu/Mine tabs, live hashrate polling

1 files changed, 18 insertions, 8 deletions

diff --git a/main/tollgate_client.c b/main/tollgate_client.c
index ac8dcfe..33b108e 100644
--- a/main/tollgate_client.c
+++ b/main/tollgate_client.c
@@ -126,15 +126,25 @@ static bool parse_discovery_response(const char *json_str, tollgate_discovery_t
             if (val && cJSON_IsString(val)) {
                 out->step_size_ms = atoi(val->valuestring);
             }
-        } else if (strcmp(tag_name->valuestring, "price_per_step") == 0 && tag_len >= 6) {
-            cJSON *amount = cJSON_GetArrayItem(tag, 2);
-            cJSON *mint = cJSON_GetArrayItem(tag, 4);
+        } else if (strcmp(tag_name->valuestring, "price_per_step") == 0 && tag_len >= 4) {
+            cJSON *payment_type = cJSON_GetArrayItem(tag, 2);
+
+            if (cJSON_IsString(payment_type) && strcmp(payment_type->valuestring, "mining") == 0 && tag_len >= 5) {
+                out->mining_available = true;
+                cJSON *port_val = cJSON_GetArrayItem(tag, 3);
+                if (port_val && cJSON_IsString(port_val)) {
+                    out->mining_port = (uint16_t)atoi(port_val->valuestring);
+                }
+            } else {
+                cJSON *amount = cJSON_GetArrayItem(tag, 2);
+                cJSON *mint = cJSON_GetArrayItem(tag, 4);
 
-            if (amount && cJSON_IsString(amount)) {
-                out->price_per_step = atoi(amount->valuestring);
-            }
-            if (mint && cJSON_IsString(mint)) {
-                strncpy(out->mint_url, mint->valuestring, sizeof(out->mint_url) - 1);
+                if (amount && cJSON_IsString(amount)) {
+                    out->price_per_step = atoi(amount->valuestring);
+                }
+                if (mint && cJSON_IsString(mint)) {
+                    strncpy(out->mint_url, mint->valuestring, sizeof(out->mint_url) - 1);
+                }
             }
         }
     }