feat(control_plane): add light standby coordinator

components/control_plane/include/control_plane.h

@@ -8,6 +8,7 @@
 
 #include <stdbool.h>
 #include <stddef.h>
+#include <stdint.h>
 #include "esp_err.h"
 
 #ifdef __cplusplus
@@ -89,6 +90,35 @@ typedef struct {
     esp_err_t last_error;
 } control_plane_ota_snapshot_t;
 
+typedef enum {
+    CONTROL_PLANE_LIGHT_STANDBY_STATE_DISABLED = 0,
+    CONTROL_PLANE_LIGHT_STANDBY_STATE_ACTIVE,
+    CONTROL_PLANE_LIGHT_STANDBY_STATE_ENTERING,
+    CONTROL_PLANE_LIGHT_STANDBY_STATE_STANDBY,
+    CONTROL_PLANE_LIGHT_STANDBY_STATE_WAKING,
+    CONTROL_PLANE_LIGHT_STANDBY_STATE_STOPPED,
+} control_plane_light_standby_state_t;
+
+typedef enum {
+    CONTROL_PLANE_LIGHT_STANDBY_ACTIVITY_UNSPECIFIED = 0,
+    CONTROL_PLANE_LIGHT_STANDBY_ACTIVITY_KEY,
+    CONTROL_PLANE_LIGHT_STANDBY_ACTIVITY_LOCAL_WAKE,
+    CONTROL_PLANE_LIGHT_STANDBY_ACTIVITY_VOICE_INPUT,
+    CONTROL_PLANE_LIGHT_STANDBY_ACTIVITY_VOICE_OUTPUT,
+    CONTROL_PLANE_LIGHT_STANDBY_ACTIVITY_MODEL_COMMAND,
+    CONTROL_PLANE_LIGHT_STANDBY_ACTIVITY_EXTERNAL,
+} control_plane_light_standby_activity_t;
+
+typedef struct {
+    control_plane_light_standby_state_t state;
+    control_plane_light_standby_activity_t last_activity;
+    bool running;
+    uint32_t idle_timeout_ms;
+    uint64_t last_activity_ms;
+    uint64_t standby_since_ms;
+    uint32_t transition_count;
+} control_plane_light_standby_snapshot_t;
+
 esp_err_t control_plane_init(void);
 
 /**
@@ -109,6 +139,38 @@ esp_err_t control_plane_battery_service_start(void);
  */
 esp_err_t control_plane_prepare_runtime_storage(void);
 
+/**
+ * @brief Start the control-plane owned light-standby coordinator.
+ *
+ * The coordinator tracks one inactivity deadline for the full runtime. Phase
+ * one records state transitions only; hardware power policies are attached in
+ * later phases. Repeated starts are idempotent.
+ */
+esp_err_t control_plane_light_standby_start(void);
+
+/**
+ * @brief Stop the light-standby coordinator with bounded teardown.
+ *
+ * Zero requests asynchronous stop. Positive values wait up to the supplied
+ * timeout and apply deterministic task teardown if necessary.
+ */
+esp_err_t control_plane_light_standby_stop(int timeout_ms);
+
+/**
+ * @brief Record user activity and return the coordinator to ACTIVE state.
+ *
+ * This call is non-blocking and safe from control-plane worker tasks. It must
+ * not be called directly from an ISR.
+ */
+esp_err_t control_plane_light_standby_record_activity(
+        control_plane_light_standby_activity_t activity);
+
+/**
+ * @brief Copy the current light-standby state snapshot.
+ */
+esp_err_t control_plane_light_standby_get_snapshot(
+        control_plane_light_standby_snapshot_t *out_snapshot);
+
 /**
  * @brief Parse one direction command without side effects.
  *