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.hpp

@@ -343,6 +343,9 @@ namespace montauk::abi {
        touch in full (image decode, heap slabs). */
     static constexpr uint64_t SYS_ALLOC_EAGER          = 187;  // (bytes) -> va, 0 on failure
 
+    /* Battery.hpp -- ACPI battery status */
+    static constexpr uint64_t SYS_BATTERYINFO          = 188;  // (BatteryInfo*) -> 0, -1 no battery device
+
     /* Kernel-owned process capabilities. User identities may namespace
        per-user resources, but never participate in authorization decisions. */
     static constexpr uint64_t CAP_PROCESS_ADMIN = 1ULL << 0;
@@ -881,6 +884,26 @@ namespace montauk::abi {
         uint32_t apIdleHint;     // MWAIT hint used for AP deep idle
     };
 
+    // Battery status (returned by SYS_BATTERYINFO). A machine with no battery
+    // device fails the call outright; `present` distinguishes a laptop with the
+    // pack removed from one that is running on it.
+    struct BatteryInfo {
+        uint8_t  present;            // a battery is installed
+        uint8_t  charging;
+        uint8_t  discharging;
+        uint8_t  critical;
+        uint8_t  acOnline;           // AC adapter connected
+        uint8_t  hasAcAdapter;       // an AC adapter device exists at all
+        uint8_t  percent;            // 0..100, 0 when capacity is unknown
+        uint8_t  powerUnitMilliAmps; // capacities are mAh/mA, not mWh/mW
+        uint32_t remainingCapacity;
+        uint32_t fullCapacity;       // last full charge capacity
+        uint32_t designCapacity;
+        uint32_t presentRate;        // mW or mA, 0 when unknown
+        uint32_t voltageMv;
+        int32_t  minutesRemaining;   // -1 when not estimable (e.g. charging)
+    };
+
     // Crash report (filled by kernel on process fault, returned via SYS_CRASH_REPORT)
     struct CrashReportInfo {
         int pid;