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/addressparser.h

@@ -16,6 +16,11 @@ struct AddressParserCallbacks {
     std::function<uint64_t(const QString& name, bool* ok)> resolveModule;
     std::function<uint64_t(uint64_t addr, bool* ok)>       readPointer;
     std::function<uint64_t(const QString& name, bool* ok)> resolveIdentifier;
+
+    // Kernel paging functions (optional — only wired when kernel provider active)
+    std::function<uint64_t(uint32_t pid, uint64_t va, bool* ok)> vtop;
+    std::function<uint64_t(uint32_t pid, bool* ok)>               cr3;
+    std::function<uint64_t(uint64_t physAddr, bool* ok)>          physRead;
 };
 
 class AddressParser {