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/schema.py

@@ -0,0 +1,143 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+配置结构定义
+
+使用 dataclass 定义所有配置项的结构和类型。
+"""
+from dataclasses import dataclass, field
+from typing import Optional
+from pathlib import Path
+
+
+@dataclass
+class ERPConfig:
+    """ERP 系统配置"""
+    url: str
+    username: str
+    password: str
+    headless: bool = True
+    ignore_https_errors: bool = True
+    auto_close_browser: bool = True
+
+    def validate(self) -> list[str]:
+        """验证配置，返回错误列表"""
+        errors = []
+        if not self.url:
+            errors.append("ERP URL 不能为空")
+        if not self.username:
+            errors.append("ERP 用户名不能为空")
+        if not self.password:
+            errors.append("ERP 密码不能为空")
+        return errors
+
+
+@dataclass
+class DatabaseConfig:
+    """数据库配置"""
+    server: str
+    database: str
+    username: str
+    password: str
+    driver: str = "ODBC Driver 18 for SQL Server"
+    trust_server_certificate: str = "yes"
+
+    def validate(self) -> list[str]:
+        """验证配置，返回错误列表"""
+        errors = []
+        if not self.server:
+            errors.append("数据库服务器地址不能为空")
+        if not self.database:
+            errors.append("数据库名称不能为空")
+        if not self.username:
+            errors.append("数据库用户名不能为空")
+        if not self.password:
+            errors.append("数据库密码不能为空")
+        return errors
+
+
+@dataclass
+class PathConfig:
+    """文件路径配置"""
+    data_dir: str
+    production_id_file: str
+    default_output: str = "离散备料计划维护_合并.xlsx"
+    validation_output: str = "物料状态校验结果.xlsx"
+
+    def validate(self) -> list[str]:
+        """验证配置，返回错误列表"""
+        errors = []
+        if not self.data_dir:
+            errors.append("数据目录路径不能为空")
+        if not self.production_id_file:
+            errors.append("ProductionID 文件路径不能为空")
+        return errors
+
+
+@dataclass
+class ExtractionConfig:
+    """数据提取配置"""
+    batch_size: int = 100
+    verbose: bool = True
+    auto_convert: bool = True
+    merge_batches: bool = True
+
+    def validate(self) -> list[str]:
+        """验证配置，返回错误列表"""
+        errors = []
+        if self.batch_size <= 0:
+            errors.append("批次大小必须大于 0")
+        if self.batch_size > 1000:
+            errors.append("批次大小不应超过 1000")
+        return errors
+
+
+@dataclass
+class AppConfig:
+    """应用总配置"""
+    erp: ERPConfig
+    database: DatabaseConfig
+    paths: PathConfig
+    extraction: ExtractionConfig
+
+    def validate(self) -> list[str]:
+        """验证所有配置，返回错误列表"""
+        errors = []
+        errors.extend(self.erp.validate())
+        errors.extend(self.database.validate())
+        errors.extend(self.paths.validate())
+        errors.extend(self.extraction.validate())
+        return errors
+
+    def to_dict(self) -> dict:
+        """转换为字典格式（用于保存到 JSON）"""
+        return {
+            "erp": {
+                "url": self.erp.url,
+                "username": self.erp.username,
+                "password": self.erp.password,
+                "headless": self.erp.headless,
+                "ignore_https_errors": self.erp.ignore_https_errors,
+                "auto_close_browser": self.erp.auto_close_browser,
+            },
+            "database": {
+                "server": self.database.server,
+                "database": self.database.database,
+                "username": self.database.username,
+                "password": self.database.password,
+                "driver": self.database.driver,
+                "trust_server_certificate": self.database.trust_server_certificate,
+            },
+            "paths": {
+                "data_dir": self.paths.data_dir,
+                "production_id_file": self.paths.production_id_file,
+                "default_output": self.paths.default_output,
+                "validation_output": self.paths.validation_output,
+            },
+            "extraction": {
+                "batch_size": self.extraction.batch_size,
+                "verbose": self.extraction.verbose,
+                "auto_convert": self.extraction.auto_convert,
+                "merge_batches": self.extraction.merge_batches,
+            }
+        }