Add open command to open tech stack in default browser

Add a new 'stacktodate open' command that opens the project's tech stack page
on StackToDate in the user's default web browser.

Features:
- Reads project UUID from stacktodate.yml
- Opens https://stacktodate.club/tech_stacks/{uuid} in default browser
- Cross-platform support: macOS (open), Windows (start), Linux (xdg-open)
- Respects STD_API_URL environment variable for custom API endpoints
- Works with --config flag to specify custom config file path

Usage:
  stacktodate open
  stacktodate open --config /path/to/stacktodate.yml

This provides a quick way to view project details on the StackToDate website
without needing to copy-paste the UUID or remember the URL format.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Haiku 4.5 <[email protected]>

Author: ceritium

cmd/open.go

@@ -0,0 +1,63 @@
+package cmd
+
+import (
+	"fmt"
+	"os/exec"
+	"runtime"
+
+	"github.com/stacktodate/stacktodate-cli/cmd/helpers"
+	"github.com/stacktodate/stacktodate-cli/cmd/lib/cache"
+	"github.com/spf13/cobra"
+)
+
+var openCmd = &cobra.Command{
+	Use:   "open",
+	Short: "Open the tech stack in your browser",
+	Long:  `Open the project's tech stack page on StackToDate in your default web browser`,
+	Run: func(cmd *cobra.Command, args []string) {
+		// Load config to get UUID
+		config, err := helpers.LoadConfigWithDefaults(configFile, true)
+		if err != nil {
+			helpers.ExitOnError(err, "failed to load config")
+		}
+
+		// Get API URL
+		apiURL := cache.GetAPIURL()
+
+		// Build the tech stack URL
+		url := fmt.Sprintf("%s/tech_stacks/%s", apiURL, config.UUID)
+
+		// Open in default browser
+		if err := openBrowser(url); err != nil {
+			helpers.ExitOnError(err, "failed to open browser")
+		}
+
+		fmt.Printf("✓ Opening %s in your browser\n", url)
+	},
+}
+
+// openBrowser opens a URL in the default browser for the current operating system
+func openBrowser(url string) error {
+	var cmd *exec.Cmd
+
+	switch runtime.GOOS {
+	case "darwin":
+		// macOS
+		cmd = exec.Command("open", url)
+	case "windows":
+		// Windows
+		cmd = exec.Command("cmd", "/c", "start", url)
+	case "linux":
+		// Linux - try xdg-open first, then fall back to others
+		cmd = exec.Command("xdg-open", url)
+	default:
+		return fmt.Errorf("unsupported operating system: %s", runtime.GOOS)
+	}
+
+	return cmd.Run()
+}
+
+func init() {
+	rootCmd.AddCommand(openCmd)
+	openCmd.Flags().StringVarP(&configFile, "config", "c", "", "Path to stacktodate.yml config file (default: stacktodate.yml)")
+}