Clean up Arch profile: remove i3/Void-specific config and fix GNOME integration

- Remove XFCE/i3-specific packages and dotfiles from Arch path (xarchiver,
  udiskie, Thunar, xfce-polkit, clipman, screenshooter)
- Separate per-OS dotfiles: mimeapps, udiskie config, GTK theme script,
  udiskie-password, dbus-session and ssh-agent fragments moved to Void-only
- Add mimeapps.arch.list with Nautilus/GNOME associations for nymph
- Move dunst/rofi directory creation from common to profile_desktop_i3
- Add gnome-keyring PAM hooks for GDM (gdm-password) in profile_desktop_gnome
- Remove ssh-agent.service from desktop_systemd_user_services on Arch;
  drop ssh-agent dependency and hardcoded socket from emacs.service
- Add ttf-hack-nerd to Arch font packages
- Fix rustup bootstrap: use rustup-init on Void, rustup toolchain install on Arch

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ansible/inventory/group_vars/void.yml

@@ -88,10 +88,38 @@ desktop_void_dotfiles:
     src: .config/service/
     dest: .config/service/
     mode: preserve
+  - name: Thunar config
+    src: .config/Thunar/
+    dest: .config/Thunar/
+    mode: preserve
+  - name: MIME application defaults
+    src: .config/mimeapps.list
+    dest: .config/mimeapps.list
+    mode: "0644"
+  - name: Bash DBus session fragment
+    src: .bashrc.d/14-dbus-session.sh
+    dest: .bashrc.d/14-dbus-session.sh
+    mode: "0644"
+  - name: Bash SSH agent socket fragment
+    src: .bashrc.d/16-ssh-agent-socket.sh
+    dest: .bashrc.d/16-ssh-agent-socket.sh
+    mode: "0644"
   - name: Bash runit desktop fragment
     src: .bashrc.d/15-runit-desktop.sh
     dest: .bashrc.d/15-runit-desktop.sh
     mode: "0644"
+  - name: GTK theme setup script
+    src: .local/bin/setup-gtk-theme
+    dest: .local/bin/setup-gtk-theme
+    mode: "0755"
+  - name: Udiskie password helper
+    src: .local/bin/udiskie-password
+    dest: .local/bin/udiskie-password
+    mode: "0755"
+  - name: Udiskie config
+    src: .config/udiskie/
+    dest: .config/udiskie/
+    mode: preserve
   - name: Turnstile environment update script
     src: .local/bin/update-turnstile-env
     dest: .local/bin/update-turnstile-env