DB Migration Helper 分析 model 变更，生成安全的数据库迁移 SQL。 Overview 对比代码中的实体/模型定义与当前数据库 schema，检测结构变更（新增表、增删列、改类型），生成向前兼容的迁移 SQL。支持 MySQL、PostgreSQL、SQLite。 When to Use - User wants to create database migrations - User modified model/entity definitions - User mentions migration, schema change, or sync - User says "生成迁移" / "create migration" - User inputs When NOT to Use: - User only wants to view database structure - User wants data migration (not schema) - User uses ORM auto-migration - User wants to generate seed data - User wants to backup/restore database Core Pattern Step 1: 检测项目类型和 ORM | 检测文件 | OR…