refactor: centralize configuration management with type-safe schema

Major changes:
- Add dataclass-based configuration schema with validation (config/schema.py)
- Create centralized config loader and default values (config/defaults.py, config/loader.py)
- Remove duplicate database_config.py, merge into unified structure
- Consolidate browser settings into ERP config
- Add batch_size parameter support to extractor

Bug fixes:
- Fix settings save error by updating config paths (browser.* → erp.*)
- Fix batch_size not being applied in data extraction

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

config/loader.py

@@ -0,0 +1,138 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+配置加载器
+
+负责加载、合并和验证配置。
+"""
+import json
+import os
+from typing import Any, Dict
+from config.schema import AppConfig
+from config.defaults import DEFAULT_APP_CONFIG, DEFAULT_SETTINGS_DICT
+
+
+class ConfigLoader:
+    """配置加载器"""
+
+    @staticmethod
+    def load(config_file: str = "config/user_settings.json") -> AppConfig:
+        """
+        加载配置文件
+
+        Args:
+            config_file: 配置文件路径
+
+        Returns:
+            应用配置对象
+        """
+        if os.path.exists(config_file):
+            try:
+                with open(config_file, 'r', encoding='utf-8') as f:
+                    loaded_settings = json.load(f)
+                # 合并默认配置和加载的配置
+                merged_settings = ConfigLoader._merge_settings(DEFAULT_SETTINGS_DICT, loaded_settings)
+                return ConfigLoader._dict_to_config(merged_settings)
+            except (json.JSONDecodeError, IOError) as e:
+                print(f"加载配置文件失败: {e}，使用默认配置")
+                return DEFAULT_APP_CONFIG
+        else:
+            # 首次运行，创建默认配置文件
+            ConfigLoader.save(DEFAULT_APP_CONFIG, config_file)
+            return DEFAULT_APP_CONFIG
+
+    @staticmethod
+    def save(config: AppConfig, config_file: str = "config/user_settings.json") -> bool:
+        """
+        保存配置到文件
+
+        Args:
+            config: 应用配置对象
+            config_file: 配置文件路径
+
+        Returns:
+            保存是否成功
+        """
+        try:
+            # 确保配置目录存在
+            os.makedirs(os.path.dirname(config_file), exist_ok=True)
+
+            with open(config_file, 'w', encoding='utf-8') as f:
+                json.dump(config.to_dict(), f, ensure_ascii=False, indent=2)
+            return True
+        except IOError as e:
+            print(f"保存配置文件失败: {e}")
+            return False
+
+    @staticmethod
+    def _merge_settings(defaults: Dict, loaded: Dict) -> Dict:
+        """
+        合并默认配置和加载的配置
+
+        Args:
+            defaults: 默认配置
+            loaded: 加载的配置
+
+        Returns:
+            合并后的配置
+        """
+        result = defaults.copy()
+
+        for key, value in loaded.items():
+            if key in result and isinstance(result[key], dict) and isinstance(value, dict):
+                result[key] = ConfigLoader._merge_settings(result[key], value)
+            else:
+                result[key] = value
+
+        return result
+
+    @staticmethod
+    def _dict_to_config(settings: Dict) -> AppConfig:
+        """
+        将字典转换为配置对象
+
+        Args:
+            settings: 配置字典
+
+        Returns:
+            应用配置对象
+        """
+        erp_dict = settings.get("erp", {})
+        database_dict = settings.get("database", {})
+        paths_dict = settings.get("paths", {})
+        extraction_dict = settings.get("extraction", {})
+
+        return AppConfig(
+            erp=ERPConfig(
+                url=erp_dict.get("url", ""),
+                username=erp_dict.get("username", ""),
+                password=erp_dict.get("password", ""),
+                headless=erp_dict.get("headless", True),
+                ignore_https_errors=erp_dict.get("ignore_https_errors", True),
+                auto_close_browser=erp_dict.get("auto_close_browser", True),
+            ),
+            database=DatabaseConfig(
+                server=database_dict.get("server", ""),
+                database=database_dict.get("database", ""),
+                username=database_dict.get("username", ""),
+                password=database_dict.get("password", ""),
+                driver=database_dict.get("driver", "ODBC Driver 18 for SQL Server"),
+                trust_server_certificate=database_dict.get("trust_server_certificate", "yes"),
+            ),
+            paths=PathConfig(
+                data_dir=paths_dict.get("data_dir", ""),
+                production_id_file=paths_dict.get("production_id_file", ""),
+                default_output=paths_dict.get("default_output", "离散备料计划维护_合并.xlsx"),
+                validation_output=paths_dict.get("validation_output", "物料状态校验结果.xlsx"),
+            ),
+            extraction=ExtractionConfig(
+                batch_size=extraction_dict.get("batch_size", 100),
+                verbose=extraction_dict.get("verbose", True),
+                auto_convert=extraction_dict.get("auto_convert", True),
+                merge_batches=extraction_dict.get("merge_batches", True),
+            )
+        )
+
+
+# 为了兼容旧代码，导入必要的类型
+from config.schema import ERPConfig, DatabaseConfig, PathConfig, ExtractionConfig