feat: add kernel ACPI support for querying battery percentage, add battery indicator to desktop, move log state to 0:/state directory

kernel/src/Api/Syscall.cpp

@@ -504,6 +504,12 @@ namespace montauk::abi {
             case SYS_POWERINFO:
                 if (!UserMemory::Writable<PowerInfo>(frame->arg1)) return -1;
                 return Sys_PowerInfo((PowerInfo*)frame->arg1);
+            case SYS_BATTERYINFO:
+                // Read-only power telemetry, ungated like SYS_POWERINFO: the
+                // panel indicator has to work in an unprivileged session, which
+                // holds no device capability to spend on it.
+                if (!UserMemory::Writable<BatteryInfo>(frame->arg1)) return -1;
+                return Sys_BatteryInfo((BatteryInfo*)frame->arg1);
             case SYS_THREAD_SPAWN:
                 return Sys_ThreadSpawn(frame->arg1, frame->arg2, frame->arg3);
             case SYS_THREAD_EXIT: