v1.2.0 — Linux Flasher, Kali Creator, fixed flashing & counterfeit detection

New features:
- Linux Flasher tab: download+decompress+flash pipeline for RPi OS, Ubuntu,
  Debian, Fedora, Kali, DietPi, Alpine, Arch ARM with built-in image catalog
- Kali Creator tab: 4 sub-tabs for USB/SD, VM creation, Docker/Podman
  container pulls, and cloud image downloads
- DownloadManager: async downloads with resume support and speed tracking
- Decompressor: streaming .xz (xz-embedded), .gz (zlib), .zip decompression
- ImageCatalog: built-in catalog + remote fetch from rpi-imager JSON endpoint
- SevenZipExtractor: QProcess wrapper for 7z.exe with progress parsing
- Bundled xz-embedded third-party library for native XZ decompression

Bug fixes:
- Fixed VirtualDisk::flashToDisk() — added FSCTL_ALLOW_EXTENDED_DASD_IO,
  FSCTL_LOCK_VOLUME, FSCTL_DISMOUNT_VOLUME, 32MB aligned buffers,
  WriteFile retry logic (3 attempts), FlushFileBuffers before close
- Fixed VirtualDisk::captureFromDisk() with same improvements
- Fixed ImagingTab::onFlashIso() — now populates targetVolumeLetters from
  disk snapshot so IsoFlasher can properly lock/dismount volumes
- Fixed SD card counterfeit detection false positives:
  - Changed from write-one-read-one to write-all-then-read-all algorithm
    to properly detect NAND address wrapping on fake cards
  - Added volume lock/dismount before probing to prevent filesystem
    interference (journal writes, metadata updates)
  - Added FSCTL_ALLOW_EXTENDED_DASD_IO for probes near end of disk
  - Fixed overly aggressive vendor string check — USB card readers
    legitimately report "USB"/"Mass Storage", no longer flagged
  - Added handle re-open between write and verify phases to defeat
    USB reader hardware cache
- README: documented how to unlock the secret menu, added new feature docs

src/ui/MainWindow.h

@@ -18,6 +18,11 @@ class ImagingTab;
 class DiagnosticsTab;
 class SecurityTab;
 class MaintenanceTab;
+class SdCardTab;
+class VirtualDiskTab;
+class NonWindowsFsTab;
+class LinuxFlasherTab;
+class KaliCreatorTab;
 
 class MainWindow : public QMainWindow
 {
@@ -43,6 +48,7 @@ private:
 private slots:
     void onAbout();
     void onRefreshDisks();
+    void onUnlockFeatures();
     void onStatusMessage(const QString& msg);
 
 private:
@@ -56,6 +62,11 @@ private:
     DiagnosticsTab* m_diagnosticsTab = nullptr;
     SecurityTab* m_securityTab = nullptr;
     MaintenanceTab* m_maintenanceTab = nullptr;
+    SdCardTab* m_sdCardTab = nullptr;
+    VirtualDiskTab* m_virtualDiskTab = nullptr;
+    NonWindowsFsTab* m_nonWinFsTab = nullptr;
+    LinuxFlasherTab* m_linuxFlasherTab = nullptr;
+    KaliCreatorTab* m_kaliCreatorTab = nullptr;
 
     // Hardware diagnostics module (vendor library)
     QWidget* m_hwdiagPanel = nullptr;