feat(version): add version command to display version and build date

cmd/relspec/root.go

@@ -1,9 +1,17 @@
 package main
 
 import (
+	"fmt"
+
 	"github.com/spf13/cobra"
 )
 
+var (
+	// Version information, set via ldflags during build
+	version   = "dev"
+	buildDate = "unknown"
+)
+
 var rootCmd = &cobra.Command{
 	Use:   "relspec",
 	Short: "RelSpec - Database schema conversion and analysis tool",
@@ -13,6 +21,9 @@ bidirectional conversion between various database schema formats.
 It reads database schemas from multiple sources (live databases, DBML,
 DCTX, DrawDB, etc.) and writes them to various formats (GORM, Bun,
 JSON, YAML, SQL, etc.).`,
+	PersistentPreRun: func(cmd *cobra.Command, args []string) {
+		fmt.Printf("RelSpec %s (built: %s)\n\n", version, buildDate)
+	},
 }
 
 func init() {
@@ -24,4 +35,5 @@ func init() {
 	rootCmd.AddCommand(editCmd)
 	rootCmd.AddCommand(mergeCmd)
 	rootCmd.AddCommand(splitCmd)
+	rootCmd.AddCommand(versionCmd)
 }