refactor: implement UI code optimization and refactoring

This commit implements the comprehensive UI code refactoring plan to improve
code quality, reduce duplication, and enhance maintainability.

Phase 1: High Priority Improvements
- Create BaseDialog class to eliminate window centering code duplication
  across ProgressDialog, DeleteProgressWindow, LoginDialog, and
  UserSelectionDialog (~30 lines of duplicate code removed)
- Unify log color configuration with LogTheme class in gui/log_config.py
- Create permission check decorators (@require_admin, @require_permission,
  @require_user_type, @handle_errors)
- Update all dialog classes to use unified patterns

Phase 2: Architecture Improvements
- Create input validation framework (ValidationResult, Validator,
  ValidatedWidget classes)
- Implement StateManager with observer pattern for component state sharing
- Create unified ErrorHandler for consistent error handling
- Extract CheckboxTreeview into reusable component

New Modules:
- gui/widgets/base_dialog.py - Base dialog class with modal setup and centering
- gui/utils/decorators.py - Permission and error handling decorators
- gui/utils/error_handler.py - Unified error handling with user-friendly messages
- gui/utils/state_manager.py - State management with observer pattern
- gui/utils/validators.py - Input validation framework
- gui/material_validation/checkbox_treeview.py - Reusable checkbox table

Modified Files:
- gui/log_config.py - Added LogTheme class for centralized styling
- gui/widgets/log_text.py - Use LogTheme.COLORS
- gui/widgets/progress_dialog.py - Inherit from BaseDialog
- gui/widgets/delete_progress_window.py - Inherit from BaseDialog, use LogTheme
- gui/widgets/__init__.py - Add new exports, optional imports
- gui/login_dialog.py - Use unified centering pattern
- gui/user_selection_dialog.py - Use unified centering pattern
- gui/material_validation_tab.py - Import CheckboxTreeview from new module

Benefits:
- Reduced code duplication by ~200 lines
- Improved maintainability through centralized configuration
- Better abstraction with 5 new reusable base classes
- Enhanced type safety with type hints
- Future-proof theming support via LogTheme

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

gui/widgets/log_text.py

@@ -8,19 +8,14 @@
 
 import tkinter as tk
 from datetime import datetime
+from gui.log_config import LogTheme
 
 
 class LogText(tk.Frame):
     """日志文本框组件（带滚动条）"""
 
-    # 日志级别颜色配置
-    LOG_COLORS = {
-        'INFO': '#000000',      # 黑色
-        'SUCCESS': '#008000',   # 绿色
-        'WARNING': '#FF8C00',   # 深橙色
-        'ERROR': '#FF0000',     # 红色
-        'DEBUG': '#808080',     # 灰色
-    }
+    # 使用统一日志主题配置
+    LOG_COLORS = LogTheme.COLORS
 
     def __init__(self, parent, readonly=True, **kwargs):
         """