feat(desktop): consolidate declarative workstation profile

Capture desktop-specific system, session, Noctalia, and Pi integration alongside shared laptop support. Retire obsolete X11 configuration and make package ownership explicit for repeatable Decman deployments.

system-config/packages/desktop/local-aur.txt

@@ -0,0 +1,5 @@
+beads
+downgrade
+nomacs-git
+yay-debug
+zsa-keymapp-bin

system-config/packages/desktop/local-repo.txt

@@ -0,0 +1,34 @@
+bun
+fakeroot
+geoclue
+github-cli
+gtk4-layer-shell
+lsof
+lvm2
+mpv
+numlockx
+nvidia-container-toolkit
+nvidia-settings
+ollama-cuda
+opencode
+perl-yaml-tiny
+pipewire
+powerline
+qpwgraph
+ranger
+retry
+rustup
+screengrab
+seahorse
+sudo
+sway
+texlive-bin
+texlive-meta
+tree
+ttf-meslo-nerd
+unrar
+vlc-plugins-all
+vulkan-radeon
+wdisplays
+wget
+xournalpp