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

programs/src/desktop/main.cpp

@@ -392,6 +392,7 @@ void gui::desktop_init(DesktopState* ds) {
 
     desktop_refresh_netifs(ds);
     desktop_wifi_init(ds);
+    desktop_battery_init(ds);
 
     ds->vol_popup_open = false;
     ds->vol_icon_rect = {0, 0, 0, 0};
@@ -518,6 +519,7 @@ static bool desktop_refresh_panel_state(DesktopState* ds, uint64_t now) {
     }
 
     if (desktop_wifi_poll(ds, now)) changed = true;
+    if (desktop_battery_poll(ds, now)) changed = true;
 
     // Event-driven sync: the kernel mixer bumps a serial on every state
     // change. Reading it is one cheap syscall; refresh only when the serial