feat: disconnect Bluetooth devices, flush disks on shutdown/reboot, display progress in login.elf window

programs/include/montauk/syscall.h

@@ -369,6 +369,15 @@ namespace montauk {
         return (int)syscall0(Montauk::SYS_SUSPEND);
     }
 
+    // Graceful power-off request channel. The desktop posts a pending action
+    // (Montauk::POWER_REQ_SHUTDOWN / POWER_REQ_REBOOT) then exits; login.elf
+    // reads it with POWER_REQ_QUERY (read-and-clear), runs the shutdown stages,
+    // and finally calls shutdown()/reset(). Returns the pending action for a
+    // query, or 0 when posting one.
+    inline int power_request(int action) {
+        return (int)syscall1(Montauk::SYS_POWER_REQUEST, (uint64_t)(int64_t)action);
+    }
+
     // Mouse
     inline void mouse_state(Montauk::MouseState* out) { syscall1(Montauk::SYS_MOUSESTATE, (uint64_t)out); }
     inline void set_mouse_bounds(int32_t maxX, int32_t maxY) {
@@ -436,6 +445,11 @@ namespace montauk {
     inline int fs_mount(int partIndex, int driveNum) {
         return (int)syscall2(Montauk::SYS_FSMOUNT, (uint64_t)partIndex, (uint64_t)driveNum);
     }
+    // Flush all block-device write caches and cleanly unmount disk-backed
+    // volumes ahead of power-off. Returns the number of volumes unmounted.
+    inline int fs_sync() {
+        return (int)syscall0(Montauk::SYS_FS_SYNC);
+    }
     inline int fs_format(const Montauk::FsFormatParams* params) {
         return (int)syscall1(Montauk::SYS_FSFORMAT, (uint64_t)params);
     }