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

plugins/KernelMemory/linux/Makefile

@@ -0,0 +1,17 @@
+obj-m += rcxkm.o
+
+KDIR ?= /lib/modules/$(shell uname -r)/build
+
+all:
+	$(MAKE) -C $(KDIR) M=$(PWD) modules
+
+clean:
+	$(MAKE) -C $(KDIR) M=$(PWD) clean
+
+install:
+	insmod rcxkm.ko
+
+uninstall:
+	rmmod rcxkm
+
+.PHONY: all clean install uninstall