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

kernel/src/Fs/FsProbe.cpp

@@ -6,6 +6,7 @@
 
 #include "FsProbe.hpp"
 #include <Drivers/Storage/Gpt.hpp>
+#include <Drivers/Storage/BlockDevice.hpp>
 #include <Terminal/Terminal.hpp>
 #include <Libraries/Memory.hpp>
 
@@ -195,4 +196,43 @@ namespace Fs::FsProbe {
         return unmounted;
     }
 
+    int SyncAndUnmountAll() {
+        // 1. Flush every block device's volatile write cache to media. FAT32 and
+        //    ext2 are write-through, so file data already reached the device; the
+        //    flush makes the device commit it to non-volatile storage.
+        int devCount = Drivers::Storage::GetBlockDeviceCount();
+        for (int i = 0; i < devCount; i++) {
+            const auto* dev = Drivers::Storage::GetBlockDevice(i);
+            if (dev && dev->Flush) {
+                dev->Flush(dev->Ctx);
+            }
+        }
+
+        // 2. Cleanly unmount every disk-backed VFS drive. The ramdisk has no
+        //    backing block device (GetBlockDeviceForDrive < 0) and is left
+        //    mounted so the rest of userspace keeps running until power-off.
+        int drives[Vfs::MaxDrives];
+        int n = Vfs::VfsDriveList(drives, Vfs::MaxDrives);
+        int unmounted = 0;
+
+        for (int i = 0; i < n; i++) {
+            int driveNum = drives[i];
+            if (GetBlockDeviceForDrive(driveNum) < 0) continue;
+
+            if (Vfs::UnregisterDrive(driveNum) == 0) {
+                unmounted++;
+                for (int p = 0; p < Drivers::Storage::Gpt::MaxPartitions; p++) {
+                    if (g_mounted[p] && g_driveForPart[p] == driveNum) {
+                        g_mounted[p] = false;
+                        g_driveForPart[p] = -1;
+                    }
+                }
+            }
+        }
+
+        Kt::KernelLogStream(Kt::OK, "FsProbe") << "Synced and unmounted "
+            << unmounted << " disk-backed volume(s) for power-off";
+        return unmounted;
+    }
+
 };