feat(ble): Only update BAS when active

As a further mitigation against spurious wakeups without having to disable the battery service entirely, the battery percentage can only be updated when the board is active i.e. when in use, which infers the computer is also in use

app/src/battery.c

@@ -18,6 +18,7 @@ LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 #include <zmk/event_manager.h>
 #include <zmk/battery.h>
 #include <zmk/events/battery_state_changed.h>
+#include <zmk/activity.h>
 #include <zmk/workqueue.h>
 
 static uint8_t last_state_of_charge = 0;
@@ -52,13 +53,15 @@ static int zmk_battery_update(const struct device *battery) {
     if (last_state_of_charge != state_of_charge.val1) {
         last_state_of_charge = state_of_charge.val1;
 #if IS_ENABLED(CONFIG_BT_BAS)
-        LOG_DBG("Setting BAS GATT battery level to %d.", last_state_of_charge);
+        if (zmk_activity_get_state() == ZMK_ACTIVITY_ACTIVE) {
+            LOG_DBG("Setting BAS GATT battery level to %d.", last_state_of_charge);
 
-        rc = bt_bas_set_battery_level(last_state_of_charge);
+            rc = bt_bas_set_battery_level(last_state_of_charge);
 
-        if (rc != 0) {
-            LOG_WRN("Failed to set BAS GATT battery level (err %d)", rc);
-            return rc;
+            if (rc != 0) {
+                LOG_WRN("Failed to set BAS GATT battery level (err %d)", rc);
+                return rc;
+            }
         }
 #endif
         rc = ZMK_EVENT_RAISE(new_zmk_battery_state_changed(