Remove i3 desktop profile and st terminal

Elimina completamente la sessione desktop i3 (X11), ormai non più usata
(gli host espongono solo sway e Hyprland su Wayland):
- ruolo profile_desktop_i3 e voce emptty i3.desktop
- desktop_i3_packages e i guard 'i3' in desktop_sessions_enabled
- desktop_i3_dotfiles e host_i3_dotfiles (autorandr X11)
- dotfiles i3/X11: .xinitrc, i3, i3blocks, picom, polybar, autorandr
- task host-specifici i3 (copy dotfiles, wrap prime-run su nymph)
- rimuove st (terminale X11 da sorgente) da desktop_void_source_tools
- consolida lo script live in scripts/remove_i3.sh, elimina cleanup-i3.sh
- aggiorna la documentazione (README/AGENTS/CLAUDE/knowledge)

Config Emacs lasciata invariata di proposito.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ansible/inventory/group_vars/desktop.yml

@@ -140,44 +140,6 @@ desktop_emacs_dotfiles:
     dest: .emacs.d/
     mode: preserve
 
-desktop_i3_dotfiles:
-  - name: i3 config
-    src: .config/i3/
-    dest: .config/i3/
-    mode: preserve
-  - name: dunst config
-    src: .config/dunst/
-    dest: .config/dunst/
-    mode: preserve
-  - name: i3blocks config
-    src: .config/i3blocks/
-    dest: .config/i3blocks/
-    mode: preserve
-  - name: rofi config
-    src: .config/rofi/
-    dest: .config/rofi/
-    mode: preserve
-  - name: picom config
-    src: .config/picom/picom.conf
-    dest: .config/picom/picom.conf
-    mode: "0644"
-  - name: polybar config
-    src: .config/polybar/config.ini
-    dest: .config/polybar/config.ini
-    mode: "0644"
-  - name: polybar launcher
-    src: .config/polybar/launch.sh
-    dest: .config/polybar/launch.sh
-    mode: "0755"
-  - name: alacritty config
-    src: .config/alacritty/
-    dest: .config/alacritty/
-    mode: preserve
-  - name: .xinitrc
-    src: .xinitrc
-    dest: .xinitrc
-    mode: "0644"
-
 desktop_sway_dotfiles:
   - name: alacritty config
     src: .config/alacritty/