feat: implement user type-based UI access control

Restrict settings interface and material validation features based on user type:

- SettingsTab: User type only sees "Test ERP Connection" and "Test Database Connection" buttons; Admin sees full configuration interface
- MaterialValidationTab: Hide manager filter and data source options from non-admin users; default to database_filtered mode
- test_db_connection(): Read from config directly to support User type without UI variables
- Add backward compatibility: no session_manager defaults to full interface

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

gui/main_window.py

@@ -83,8 +83,8 @@ class MainWindow:
         self.query_tab = DataQueryTab(self.notebook, self.config)
         self.notebook.add(self.query_tab, text="数据查询")
 
-        # 设置标签页
-        self.settings_tab = SettingsTab(self.notebook, self.config)
+        # 设置标签页（传入 session_manager）
+        self.settings_tab = SettingsTab(self.notebook, self.config, self.session_manager)
         self.notebook.add(self.settings_tab, text="设置")
 
     def create_status_bar(self):