refactor: abstract database layer to support MySQL and SQL Server

- Add IDatabaseService interface with unified query(transaction) methods
- Create DatabaseFactory for centralized database service creation
- Modify MySqlService and SqlServerService to implement IDatabaseService
- Unify SqlServerService.query() to accept array params (internally converts to @p0, @p1...)
- Refactor OrderNumberResolver to use IDatabaseService
- Refactor DiscreteMaterialPlanDAO to use DatabaseFactory
- Refactor MaterialsToBeDeletedDAO to use DatabaseFactory
- Update IPC handlers to use DatabaseFactory.create()
- Add database.types.ts with shared type definitions

This enables switching between MySQL and SQL Server via DB_TYPE env variable.

Co-Authored-By: Claude (glm-5) <noreply@anthropic.com>

src/main/types/database.types.ts

@@ -0,0 +1,104 @@
+/**
+ * Database Type Definitions
+ *
+ * Provides abstract interfaces for database operations,
+ * supporting both MySQL and SQL Server databases.
+ */
+
+/**
+ * Supported database types
+ */
+export type DatabaseType = 'mysql' | 'sqlserver'
+
+/**
+ * Standard query result interface
+ */
+export interface QueryResult {
+  /** Query result rows */
+  rows: Record<string, unknown>[]
+  /** Column names from the query */
+  columns: string[]
+  /** Number of rows affected or returned */
+  rowCount: number
+}
+
+/**
+ * Database service interface
+ *
+ * Defines the common interface that all database services must implement.
+ * This allows for database-agnostic operations throughout the application.
+ */
+export interface IDatabaseService {
+  /** Database type identifier */
+  readonly type: DatabaseType
+
+  /**
+   * Connect to the database
+   */
+  connect(): Promise<void>
+
+  /**
+   * Disconnect from the database
+   */
+  disconnect(): Promise<void>
+
+  /**
+   * Check if connected to the database
+   */
+  isConnected(): boolean
+
+  /**
+   * Execute a query and return results
+   * @param sql - SQL query string
+   * @param params - Query parameters as an array
+   */
+  query(sql: string, params?: any[]): Promise<QueryResult>
+
+  /**
+   * Execute multiple queries in a transaction
+   * @param queries - Array of queries with optional parameters
+   */
+  transaction(queries: { sql: string; params?: any[] }[]): Promise<void>
+}
+
+/**
+ * Base database configuration interface
+ */
+export interface DatabaseConfig {
+  /** Database server host */
+  host?: string
+  /** Database server port */
+  port?: number
+  /** Database username */
+  user?: string
+  /** Database password */
+  password?: string
+  /** Database name */
+  database?: string
+}
+
+/**
+ * MySQL-specific configuration
+ */
+export interface MySqlConfig extends DatabaseConfig {
+  host: string
+  port: number
+  user: string
+  password: string
+  database: string
+}
+
+/**
+ * SQL Server-specific configuration
+ */
+export interface SqlServerConfig extends DatabaseConfig {
+  server: string
+  port: number
+  user: string
+  password: string
+  database: string
+  options?: {
+    encrypt?: boolean
+    trustServerCertificate?: boolean
+  }
+}