fix: surface zoitechat.conf/colors.conf save failures; add missing theme prefs fwd decl

src/fe-gtk/theme/tests/test-theme-access-routing.c

@@ -57,9 +57,10 @@ theme_runtime_load (void)
 {
 }
 
-void
+gboolean
 theme_runtime_save (void)
 {
+	return TRUE;
 }
 
 void

src/fe-gtk/theme/tests/test-theme-manager-auto-refresh.c

@@ -119,8 +119,9 @@ void theme_runtime_load (void)
 {
 }
 
-void theme_runtime_save (void)
+gboolean theme_runtime_save (void)
 {
+	return TRUE;
 }
 
 gboolean theme_runtime_is_dark_active (void)

src/fe-gtk/theme/tests/test-theme-manager-dispatch-routing.c

@@ -112,8 +112,9 @@ void theme_runtime_load (void)
 {
 }
 
-void theme_runtime_save (void)
+gboolean theme_runtime_save (void)
 {
+	return TRUE;
 }
 
 gboolean theme_runtime_is_dark_active (void)

src/fe-gtk/theme/tests/test-theme-manager-policy.c

@@ -122,8 +122,9 @@ void theme_runtime_load (void)
 {
 }
 
-void theme_runtime_save (void)
+gboolean theme_runtime_save (void)
 {
+	return TRUE;
 }
 
 gboolean theme_runtime_is_dark_active (void)

src/fe-gtk/theme/tests/test-theme-preferences-gtk3-populate.c

@@ -66,9 +66,10 @@ theme_manager_reset_mode_colors (unsigned int mode, gboolean *palette_changed)
                 *palette_changed = FALSE;
 }
 
-void
+gboolean
 theme_manager_save_preferences (void)
 {
+	return TRUE;
 }
 
 ThemePaletteBehavior