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/parse.go

@@ -0,0 +1,71 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/insertr/cli/pkg/parser"
+	"github.com/spf13/cobra"
+)
+
+var parseCmd = &cobra.Command{
+	Use:   "parse [input-dir]",
+	Short: "Parse HTML files and detect editable elements",
+	Long: `Parse HTML files in the specified directory and detect elements
+with the 'insertr' class. This command analyzes the HTML structure
+and reports what editable elements would be enhanced.`,
+	Args: cobra.ExactArgs(1),
+	Run: func(cmd *cobra.Command, args []string) {
+		inputDir := args[0]
+
+		if _, err := os.Stat(inputDir); os.IsNotExist(err) {
+			fmt.Fprintf(os.Stderr, "Error: Directory %s does not exist\n", inputDir)
+			os.Exit(1)
+		}
+
+		fmt.Printf("🔍 Parsing HTML files in: %s\n\n", inputDir)
+
+		p := parser.New()
+		result, err := p.ParseDirectory(inputDir)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Error parsing directory: %v\n", err)
+			os.Exit(1)
+		}
+
+		printParseResults(result)
+	},
+}
+
+func printParseResults(result *parser.ParseResult) {
+	fmt.Printf("📊 Parse Results:\n")
+	fmt.Printf("   Files processed: %d\n", result.Stats.FilesProcessed)
+	fmt.Printf("   Elements found: %d\n", result.Stats.TotalElements)
+	fmt.Printf("   Existing IDs: %d\n", result.Stats.ExistingIDs)
+	fmt.Printf("   Generated IDs: %d\n", result.Stats.GeneratedIDs)
+
+	if len(result.Stats.TypeBreakdown) > 0 {
+		fmt.Printf("\n📝 Content Types:\n")
+		for contentType, count := range result.Stats.TypeBreakdown {
+			fmt.Printf("   %s: %d\n", contentType, count)
+		}
+	}
+
+	if len(result.Elements) > 0 {
+		fmt.Printf("\n🎯 Found Elements:\n")
+		for _, element := range result.Elements {
+			fmt.Printf("   %s <%s> id=%s type=%s\n",
+				filepath.Base(element.FilePath),
+				element.Tag,
+				element.ContentID,
+				element.Type)
+		}
+	}
+
+	if len(result.Warnings) > 0 {
+		fmt.Printf("\n⚠️  Warnings:\n")
+		for _, warning := range result.Warnings {
+			fmt.Printf("   %s\n", warning)
+		}
+	}
+}