Fix PSP memory stick availability check on real hardware

sceIoGetstat on a bare device root ("ms0:/") returns EINVAL on real
PSP hardware even when a memory stick is present - confirmed via a
diagnostic print during hardware testing. Switched to sceIoDopen/
sceIoDclose, the SDK's own documented way to probe a device root,
which real hardware handles correctly.

Also adds a temporary unconditional settings write once a save device
is selected, to confirm the write path itself works on hardware now
that availability detection is fixed.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

src/duskpsp/save/savedevicepsp.c

@@ -38,13 +38,18 @@ void saveDevicePSPCheckAvailability(savedevice_t *device) {
 
   // Confirm the memory stick is actually reachable - the real save/load
   // (via sceUtilitySavedata) only reports failure once a save/load is
-  // attempted, so this is checked separately up front.
-  SceIoStat stat;
-  if(sceIoGetstat(SAVE_DEVICE_PSP_ROOT, &stat) < 0) {
+  // attempted, so this is checked separately up front. sceIoGetstat on a
+  // bare device root (e.g. "ms0:/") is unreliable on real hardware -
+  // confirmed returning EINVAL there even with a memory stick present -
+  // so open/close the root directory instead, which is the SDK's own
+  // documented way to probe a device (see sceIoDopen's doc comment).
+  SceUID dir = sceIoDopen(SAVE_DEVICE_PSP_ROOT);
+  if(dir < 0) {
     device->state = SAVE_DEVICE_STATE_UNAVAILABLE;
     device->reasonKey = "save.psp.no_memory_stick";
     return saveDeviceFireCallback(device);
   }
+  sceIoDclose(dir);
 
   device->state = SAVE_DEVICE_STATE_AVAILABLE;
   device->reasonKey = NULL;