feat(mining): add new mining source files and unit tests

- mining_payment.c/h: hashprice calc, share validation, per-client hashrate
- stratum_client.c/h: SV1 upstream pool connection
- stratum_proxy.c/h: local SV1 TCP server for downstream miners
- sw_miner.c/h: software SHA256d miner using mbedtls
- asic_miner.c/h: ASIC detection stub (software fallback)
- test_mining_payment.c: 23 unit tests for mining payment module

1 files changed, 63 insertions, 0 deletions

diff --git a/main/asic_miner.c b/main/asic_miner.c
new file mode 100644
index 0000000..1db6d18
--- /dev/null
+++ b/main/asic_miner.c
@@ -0,0 +1,63 @@
+#include "asic_miner.h"
+#include "esp_log.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include <string.h>
+
+static const char *TAG = "asic_miner";
+static bool s_present = false;
+static bool s_running = false;
+static TaskHandle_t s_task_handle = NULL;
+static double s_hashrate = 0.0;
+
+static void asic_miner_task(void *arg)
+{
+    ESP_LOGI(TAG, "ASIC miner task started (stub)");
+    while (s_running) {
+        vTaskDelay(pdMS_TO_TICKS(1000));
+    }
+    vTaskDelete(NULL);
+}
+
+esp_err_t asic_miner_init(void)
+{
+    s_present = false;
+    ESP_LOGI(TAG, "ASIC miner initialized - no ASIC detected (software fallback)");
+    return ESP_OK;
+}
+
+bool asic_miner_is_present(void)
+{
+    return s_present;
+}
+
+esp_err_t asic_miner_start(void)
+{
+    if (!s_present) {
+        ESP_LOGW(TAG, "No ASIC present, cannot start");
+        return ESP_FAIL;
+    }
+
+    s_running = true;
+    BaseType_t ret = xTaskCreate(asic_miner_task, "asic_miner", 4096, NULL, 3, &s_task_handle);
+    if (ret != pdPASS) {
+        ESP_LOGE(TAG, "Failed to create ASIC task");
+        s_running = false;
+        return ESP_FAIL;
+    }
+    return ESP_OK;
+}
+
+void asic_miner_stop(void)
+{
+    s_running = false;
+    if (s_task_handle) {
+        vTaskDelay(pdMS_TO_TICKS(500));
+        s_task_handle = NULL;
+    }
+}
+
+double asic_miner_get_hashrate(void)
+{
+    return s_hashrate;
+}