Add Go CLI with container expansion parser and development server

- Implement Go-based CLI for build-time HTML enhancement
- Add container expansion: div.insertr auto-expands to viable children
- Create servedev command with live development workflow
- Add Air configuration for automatic rebuilds and serving
- Enable transition from runtime JS to build-time enhancement approach

insertr-cli/cmd/root.go

@@ -0,0 +1,31 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+var rootCmd = &cobra.Command{
+	Use:   "insertr",
+	Short: "Insertr CLI - HTML enhancement for static sites",
+	Long: `Insertr CLI adds editing capabilities to static HTML sites by detecting 
+editable elements and injecting content management functionality.
+
+The tool parses HTML files, finds elements with the 'insertr' class,
+and enhances them with editing capabilities while preserving
+static site performance.`,
+	Version: "0.0.1",
+}
+
+func Execute() {
+	if err := rootCmd.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func init() {
+	rootCmd.AddCommand(parseCmd)
+}