Add runtime UV protection toggle and treat near-zero sense as external power.

Per-pod NVS enable (default off) via UART/ESP-NOW/dashboard, and skip UV latch when LiPo ADC reads ~0 mV so USB/external supply still boots.

Co-authored-by: Cursor <cursoragent@cursor.com>

main/client_registry.c

@@ -143,6 +143,7 @@ static client_slot_t *alloc_slot(const uint8_t mac[CLIENT_MAC_LEN],
         static const bma456_tap_config_t k_tap_default = BMA456_TAP_CONFIG_DEFAULT;
         slot->info.tap_config = k_tap_default;
       }
+      slot->info.uv_protection_enabled = false;
       if (out_is_new != NULL) {
         *out_is_new = true;
       }
@@ -435,6 +436,41 @@ size_t client_registry_set_tap_config_all(const bma456_tap_config_t *cfg) {
   return n;
 }
 
+esp_err_t client_registry_set_uv_protection(uint32_t client_id, bool enabled) {
+  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
+    if (s_clients[i].active && s_clients[i].info.id == client_id) {
+      s_clients[i].info.uv_protection_enabled = enabled;
+      return ESP_OK;
+    }
+  }
+  return ESP_ERR_NOT_FOUND;
+}
+
+esp_err_t client_registry_get_uv_protection(uint32_t client_id,
+                                            bool *enabled_out) {
+  if (enabled_out == NULL) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  const client_info_t *info = client_registry_find_by_id(client_id);
+  if (info == NULL) {
+    return ESP_ERR_NOT_FOUND;
+  }
+  *enabled_out = info->uv_protection_enabled;
+  return ESP_OK;
+}
+
+size_t client_registry_set_uv_protection_all(bool enabled) {
+  size_t n = 0;
+  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
+    if (!s_clients[i].active) {
+      continue;
+    }
+    s_clients[i].info.uv_protection_enabled = enabled;
+    n++;
+  }
+  return n;
+}
+
 static void clear_client_accel(client_slot_t *slot) {
   if (slot == NULL) {
     return;