feat(mssql): add MSSQL writer for generating DDL from database schema

- Implement MSSQL writer to generate SQL scripts for creating schemas, tables, and constraints.
- Support for identity columns, indexes, and extended properties.
- Add tests for column definitions, table creation, primary keys, foreign keys, and comments.
- Include testing guide and sample schema for integration tests.

cmd/relspec/convert.go

@@ -18,6 +18,7 @@ import (
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/gorm"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/graphql"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/json"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/mssql"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/pgsql"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/prisma"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/sqlite"
@@ -32,6 +33,7 @@ import (
 	wgorm "git.warky.dev/wdevs/relspecgo/pkg/writers/gorm"
 	wgraphql "git.warky.dev/wdevs/relspecgo/pkg/writers/graphql"
 	wjson "git.warky.dev/wdevs/relspecgo/pkg/writers/json"
+	wmssql "git.warky.dev/wdevs/relspecgo/pkg/writers/mssql"
 	wpgsql "git.warky.dev/wdevs/relspecgo/pkg/writers/pgsql"
 	wprisma "git.warky.dev/wdevs/relspecgo/pkg/writers/prisma"
 	wsqlite "git.warky.dev/wdevs/relspecgo/pkg/writers/sqlite"
@@ -72,6 +74,7 @@ Input formats:
   - prisma: Prisma schema files (.prisma)
   - typeorm: TypeORM entity files (TypeScript)
   - pgsql: PostgreSQL database (live connection)
+  - mssql: Microsoft SQL Server database (live connection)
   - sqlite: SQLite database file
 
 Output formats:
@@ -87,6 +90,7 @@ Output formats:
   - prisma: Prisma schema files (.prisma)
   - typeorm: TypeORM entity files (TypeScript)
   - pgsql: PostgreSQL SQL schema
+  - mssql: Microsoft SQL Server SQL schema
   - sqlite: SQLite SQL schema (with automatic schema flattening)
 
 Connection String Examples:
@@ -309,6 +313,12 @@ func readDatabaseForConvert(dbType, filePath, connString string) (*models.Databa
 		}
 		reader = graphql.NewReader(&readers.ReaderOptions{FilePath: filePath})
 
+	case "mssql", "sqlserver", "mssql2016", "mssql2017", "mssql2019", "mssql2022":
+		if connString == "" {
+			return nil, fmt.Errorf("connection string is required for MSSQL format")
+		}
+		reader = mssql.NewReader(&readers.ReaderOptions{ConnectionString: connString})
+
 	case "sqlite", "sqlite3":
 		// SQLite can use either file path or connection string
 		dbPath := filePath
@@ -375,6 +385,9 @@ func writeDatabase(db *models.Database, dbType, outputPath, packageName, schemaF
 	case "pgsql", "postgres", "postgresql", "sql":
 		writer = wpgsql.NewWriter(writerOpts)
 
+	case "mssql", "sqlserver", "mssql2016", "mssql2017", "mssql2019", "mssql2022":
+		writer = wmssql.NewWriter(writerOpts)
+
 	case "sqlite", "sqlite3":
 		writer = wsqlite.NewWriter(writerOpts)