feat: kernel memory plugin + unified source menu + driver improvements

- KernelMemory plugin: kernel-mode process/physical memory R/W via IOCTL driver
- rcxdrv.sys: MmCopyMemory for reads, MDL mapping with correct cache types
  (MmCached for RAM, MmNonCached for MMIO only — fixes cache corruption BSOD)
- Driver reconnect: ensureDriverLoaded tries device handle first, no auto
  stop+delete cycle. Manual unload closes handle only, service stays running.
- Unified source menu: ProviderRegistry::populateSourceMenu() shared by both
  main window Data Source menu and RcxEditor inline picker (icons + dll names)
- IProviderPlugin::populatePluginMenu() for conditional plugin actions
  (e.g. "Unload Kernel Driver" only when loaded)
- Physical memory mode removed from selectTarget (access via context menu only)
- requestOpenProviderTab sets base address from provider after template load
- Address parser: vtop(), cr3(), physRead() callbacks for kernel paging expressions

src/editor.h

@@ -1,5 +1,6 @@
 #pragma once
 #include "core.h"
+#include "providerregistry.h"
 #include "themes/theme.h"
 #include <QWidget>
 #include <QSet>
@@ -12,11 +13,6 @@ class QsciLexerCPP;
 
 namespace rcx {
 
-struct SavedSourceDisplay {
-    QString text;
-    bool active = false;
-};
-
 class RcxEditor : public QWidget {
     Q_OBJECT
 public: