Palette: reopen the last chosen kit instead of starting empty

The chosen kit is remembered in editor.properties [Palette]; a file without it
opens on its first kit. Saving preferences now keeps the other sections.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

main.py

@@ -2980,6 +2980,8 @@ def populate_palette_types(event=None):
         return
 
     kit_name = palette_kit_names[index]
+    if event is not None and kit_name != app_state.LAST_PALETTE_KIT:
+        app_state.save_last_palette_kit(kit_name)
     types = palette.list_component_types(kit_name)
 
     for type_name, base in types:
@@ -3024,9 +3026,13 @@ def refresh_palette_kits():
         palette_kit_var.set("")
         return
 
-    palette_status.config(text=f"{len(palette_kit_names)} kits")
-    palette_kit_var.set("")
-    fit_tree_column(palette_tree)
+    # Reopen the kit chosen last so the palette is never left empty; a file without that
+    # kit opens on its first kit instead, without forgetting the remembered one.
+    if app_state.LAST_PALETTE_KIT in palette_kit_names:
+        palette_kit_combo.current(palette_kit_names.index(app_state.LAST_PALETTE_KIT))
+    else:
+        palette_kit_combo.current(0)
+    populate_palette_types()