refactor(db): use SqlDialect in MaterialsToBeDeletedDAO

Replace all isSqlServer/if-else branches with SqlDialect calls:
- Table name via dialect.quoteTableName()
- Placeholders via dialect.param() and dialect.params()
- UPSERT via dialect.upsert() in upsertMaterial(), upsertBatch(), updateManager()
- Remove buildPlaceholders(), TABLE_NAME_SQLSERVER, TABLE_NAME_MYSQL
- Re-export SqlDialect type from dialects barrel

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main/services/database/dialects/index.ts

@@ -14,6 +14,7 @@ import { SqlServerDialect } from './sqlserver-dialect'
 export { MySqlDialect } from './mysql-dialect'
 export { PostgreSqlDialect } from './postgresql-dialect'
 export { SqlServerDialect } from './sqlserver-dialect'
+export type { SqlDialect } from '@types/sql-dialect.types'
 
 export function createDialect(type: DatabaseType): SqlDialect {
   switch (type) {