Made the gtk3 Meson option effectively deprecated by forcing it to true and updating its description to state GTK3 is always used (option ignored), so users are no longer guided toward GTK2 expectations. Also updated the AppIndicator option help text to refer to GTK frontend builds generally.

Removed the GTK2 fallback branch in src/fe-gtk/meson.build, so the GTK frontend now always resolves gtk_dep from dependency('gtk+-3.0', version: '>= 3.22') and always defines -DHAVE_GTK3.

Kept AppIndicator logic gated for non-Windows builds and intact in behavior (Ayatana first, then AppIndicator, with error on enabled if neither is found).

Simplified non-Windows GDK X11 probing to always use gdk-x11-3.0, consistent with GTK3-only frontend builds.

meson_options.txt

@@ -2,8 +2,13 @@
 option('gtk-frontend', type: 'boolean',
   description: 'Main graphical interface'
 )
+<<<<<<< ours
 option('gtk3', type: 'boolean', value: true, deprecated: true,
   description: 'Deprecated: GTK frontend always builds against GTK 3'
+=======
+option('gtk3', type: 'boolean', value: true,
+  description: 'Deprecated: GTK frontend is always built against GTK 3 (option is ignored)'
+>>>>>>> theirs
 )
 option('text-frontend', type: 'boolean', value: false,
   description: 'Text interface (not generally useful)'
@@ -23,7 +28,11 @@ option('libcanberra', type: 'feature', value: 'auto',
   description: 'Support for sound alerts, Unix only'
 )
 option('appindicator', type: 'feature', value: 'auto',
+<<<<<<< ours
   description: 'Use Ayatana/AppIndicator-based tray backend for GTK frontend (non-Windows only)'
+=======
+  description: 'Use Ayatana/AppIndicator-based tray backend for GTK frontend builds'
+>>>>>>> theirs
 )
 
 # Install options