fix: refresh settings data when navigating to settings view

Extract data loading into a refresh() method on SettingsView and call it
on view switch so categories, rules, and household data stay current.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/ui/main_window.py

@@ -65,6 +65,8 @@ class MainWindow(QMainWindow):
 
     def _switch_view(self, key: str):
         self.stack.setCurrentIndex(self._views[key])
+        if key == "settings":
+            self._settings_view.refresh()
 
     def _apply_theme(self, theme: str):
         qss_path = Path(__file__).parent / "themes" / f"{theme}.qss"

src/ui/settings_view.py

@@ -39,6 +39,10 @@ class SettingsView(QWidget):
         self._build_csv_mappings_tab()
 
         # Initial data load
+        self.refresh()
+
+    def refresh(self):
+        """Reload all settings data from the database."""
         self._load_categories()
         self._load_rules()
         self._load_household()