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, 3 insertions, 0 deletions

diff --git a/main/tollgate_client.h b/main/tollgate_client.h
index 2055e52..ccee624 100644
--- a/main/tollgate_client.h
+++ b/main/tollgate_client.h
@@ -17,6 +17,7 @@ typedef enum {
     TG_CLIENT_PAYING,
     TG_CLIENT_PAID,
     TG_CLIENT_RENEWING,
+    TG_CLIENT_MINING,
     TG_CLIENT_ERROR
 } tollgate_client_state_t;
 
@@ -26,6 +27,8 @@ typedef struct {
     int step_size_ms;
     char mint_url[TG_CLIENT_MAX_MINT_URL];
     char metric[TG_CLIENT_MAX_METRIC];
+    bool mining_available;
+    uint16_t mining_port;
 } tollgate_discovery_t;
 
 esp_err_t tollgate_client_init(void);