desktop: centralize Adwaita cursor theme, fix pointer cursor on kusanagi

kusanagi set XCURSOR_THEME=Bibata-Modern-Classic but never declared the
theme in Nix — it only resolved while bibata-cursors lingered in an old
nix-env profile. Once that was gone the theme fell off the icon path and
the pointer/hand cursor disappeared.

Standardize both hosts on Adwaita (matching the shared niri config.kdl):
move XCURSOR_THEME/XCURSOR_SIZE and the adwaita-icon-theme package into
the shared profiles/desktop.nix so the theme is always on the icon path.
Drop the inert HYPRCURSOR_* vars (hyprcursor is unused under niri).

Assisted-by: Claude:claude-opus-4-8

1 files changed, 11 insertions, 0 deletions

diff --git a/profiles/desktop.nix b/profiles/desktop.nix
index e4a1fcc..6afd91d 100644
--- a/profiles/desktop.nix
+++ b/profiles/desktop.nix
@@ -141,6 +141,15 @@ in
     policies.PasswordManagerEnabled = false;
   };
 
+  # --- Cursor ---
+  # Both hosts use the Adwaita cursor theme (package below). The theme name must
+  # resolve on the icon path, else clients fall back to a themeless arrow with no
+  # pointer/hand cursor. Matches the shared niri config.kdl cursor block.
+  environment.sessionVariables = {
+    XCURSOR_THEME = "Adwaita";
+    XCURSOR_SIZE = "24";
+  };
+
   # --- Common desktop tools (system-wide to stay username-agnostic) ---
   environment.systemPackages = with pkgs; [
     ghostty # terminal — required to actually use the GUI
@@ -151,6 +160,8 @@ in
     libnotify # notify-send
     gnupg # gpg
     pinentry-gnome3 # passphrase prompt for the gpg agent
+    adwaita-icon-theme # Adwaita cursor + icon theme on the icon path (both
+    # hosts set XCURSOR_THEME=Adwaita; without this the pointer cursor is missing)
   ];
 
   # --- Fonts (base) ---