feat: implement unified logging system for GUI components

Add centralized logging mechanism that simultaneously outputs to console
and GUI log components, improving code maintainability and consistency.

Changes:
- Add gui/log_config.py for centralized logging configuration
- Add gui/widgets/log_handler.py as bridge between logging and LogText
- Integrate unified logging into DataExtractionTab and MaterialValidationTab
- Initialize logging system in MainWindow on startup
- Improve error messages in material_status_validator for empty results
- Add documentation for logging mechanism and refactoring

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

gui/log_config.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+GUI 日志配置模块
+统一配置 GUI 应用和控制台的日志输出
+"""
+import logging
+
+# 日志格式配置
+LOG_FORMAT = '%(asctime)s [%(levelname)s] %(message)s'
+DATE_FORMAT = '%Y-%m-%d %H:%M:%S'
+
+
+def setup_gui_logging(level=logging.INFO):
+    """
+    初始化 GUI 应用的日志配置
+
+    Args:
+        level: 日志级别，默认为 INFO
+
+    Returns:
+        logging.Logger: 根 logger
+    """
+    logging.basicConfig(
+        level=level,
+        format=LOG_FORMAT,
+        datefmt=DATE_FORMAT,
+        force=True  # 确保重新配置（即使之前配置过）
+    )
+    return logging.getLogger()
+
+
+def get_logger(name):
+    """
+    获取指定名称的 logger
+
+    Args:
+        name: logger 名称，通常使用 __name__
+
+    Returns:
+        logging.Logger: logger 实例
+    """
+    return logging.getLogger(name)