Reorganize desktop roles: extract common bootstrap and host-specific layers

- Add profile_desktop_common with shared desktop bootstrap (emptty, PAM,
  dotfiles, templates, GPG, Maildir, Flatpak, st, external tools)
- Add profile_desktop_host with host-specific tasks (NVIDIA/PRIME on nymph)
- Reduce profile_desktop_i3 to i3/X11-only tasks
- Create profile_desktop_hyprland for Hyprland Wayland session
- Add dual-session support (i3 + Hyprland) on nymph with session choice
- Create shared Hyprland/Waybar dotfiles under dotfiles/desktop/
- Fix Waybar: bottom position, no persistent workspaces, sort by number
- Rename host_dotfiles to host_i3_dotfiles for clarity
- Make emptty restart manual by default to avoid session drops

dotfiles/desktop/.config/hypr/hyprlock.conf

@@ -0,0 +1,46 @@
+general {
+    hide_cursor = true
+    grace = 2
+    no_fade_in = false
+}
+
+background {
+    monitor =
+    color = rgba(1f1f28ff)
+}
+
+label {
+    monitor =
+    text = cmd[update:1000] echo "$(date +'%H:%M')"
+    color = rgba(d0d0d0ff)
+    font_size = 42
+    position = 0, 80
+    halign = center
+    valign = center
+}
+
+label {
+    monitor =
+    text = cmd[update:60000] echo "$(date +'%Y-%m-%d')"
+    color = rgba(9a9a9aff)
+    font_size = 18
+    position = 0, 35
+    halign = center
+    valign = center
+}
+
+input-field {
+    monitor =
+    size = 280, 56
+    outline_thickness = 2
+    dots_size = 0.2
+    dots_spacing = 0.2
+    outer_color = rgba(4a90d9ff)
+    inner_color = rgba(1f1f28ff)
+    font_color = rgba(d0d0d0ff)
+    fade_on_empty = false
+    placeholder_text = Password...
+    position = 0, -20
+    halign = center
+    valign = center
+}