Remove GNOME dependencies and make more desktop-neutral - cleaned

- Remove gsettings-desktop-schemas dependency (GNOME-specific)
- Replace gnome.post_install() with manual gtk4-update-icon-cache
- Remove GNOME import from meson.build
- Make autostart desktop file desktop-neutral (remove GSettings condition)
- Add accessibility categories and keywords to desktop file

🤖 Generated with [Claude Code](https://claude.ai/code)

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

cthulhu-autostart.desktop.in

@@ -3,7 +3,9 @@ Type=Application
 Name=Cthulhu Screen Reader
 Exec=cthulhu
 NoDisplay=true
-AutostartCondition=GSettings org.gnome.desktop.a11y.applications screen-reader-enabled
+# Desktop-neutral autostart - no GNOME-specific conditions
+# Users can enable/disable via their desktop environment's accessibility settings
+# or by adding/removing this file from ~/.config/autostart/
 X-GNOME-AutoRestart=true
-#X-GNOME-Autostart-Phase=Initialization
-OnlyShowIn=GNOME;MATE;Unity;Cinnamon;
+Categories=Accessibility;
+Keywords=screen;reader;accessibility;speech;braille;