feat: generated and identity columns for mssql, sqlite, drizzle, typeorm, bun and gorm readers

- mssql: write computed columns (AS (expr) PERSISTED) and identity; read computed definition and identity
- sqlite: write GENERATED ALWAYS AS (expr) STORED; read generated columns via table_xinfo and parse the expression
- drizzle: generatedAlwaysAs / generated(Always|ByDefault)AsIdentity, read and write
- typeorm: asExpression/generatedType and identity decorators, read and write; decorator scan is now quote-aware
- bun, gorm readers: read generated and identity markers
- readmes updated

pkg/readers/bun/reader.go

@@ -659,6 +659,13 @@ func (r *Reader) parseColumn(fieldName string, fieldType ast.Expr, tag string, s
 			hasExplicitNullableMarker = true
 		case "autoincrement":
 			column.AutoIncrement = true
+		case "generated":
+			// GENERATED ... STORED marker written by the Bun writer; the expression is not in the tag
+			column.Generated = true
+		case "identity":
+			// GENERATED ALWAYS AS IDENTITY marker written by the Bun writer
+			column.Identity = true
+			column.IdentityGeneration = "ALWAYS"
 		case "default":
 			// Default value from Bun tag (e.g., default:gen_random_uuid())
 			column.Default = value