feat：新增MQTT控制组件和自动告警系统

- 实现MQTT控制功能，处理水泵和灯光控制指令
- 新增土壤湿度和光照强度自动告警系统，阈值可配置
- 新建MQTT控制、自动告警和阈值管理相关文件
- 更新主应用，集成MQTT和自动控制功能
- 新增传感器数据与控制状态遥测上报
- 引入NVS和应用存储分区配置

main/auto_ctrl_thresholds.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include "esp_err.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct {
+    float pump_on_soil_below_pct;
+    float pump_off_soil_above_pct;
+    float light_on_lux_below;
+    float light_off_lux_above;
+} auto_ctrl_thresholds_t;
+
+// Initializes default thresholds once at boot.
+void auto_ctrl_thresholds_init_defaults(void);
+
+// Thread-safe snapshot read, intended for control loop usage.
+void auto_ctrl_thresholds_get(auto_ctrl_thresholds_t *out);
+
+// Thread-safe full update with range/order validation.
+esp_err_t auto_ctrl_thresholds_set(const auto_ctrl_thresholds_t *cfg);
+
+// Convenience API for MQTT callback usage.
+esp_err_t auto_ctrl_thresholds_set_values(float pump_on_soil_below_pct,
+                                          float pump_off_soil_above_pct,
+                                          float light_on_lux_below,
+                                          float light_off_lux_above);
+
+#ifdef __cplusplus
+}
+#endif