Initialize project skeleton with CLI and documentation

Add initial project structure including:
- Go module with Cobra CLI dependency
- Root command and main entrypoint
- Basic documentation (README, AGENTS.md, architecture, decisions,
  development, roadmap)
- Configuration example and gitignore
- Tool version management with mise
- Comprehensive project rules and conventions

cmd/root.go

@@ -0,0 +1,28 @@
+package cmd
+
+import (
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+// rootCmd represents the base command when called without any subcommands
+var rootCmd = &cobra.Command{
+	Use:   "mygo { serve | config | status }",
+	Short: "MyGO server application",
+	Long: `MyGO is a WebDisk (Cloud Drive) server.
+This is the server (backend) application for MyGO.`,
+}
+
+// Execute adds all child commands to the root command and sets flags appropriately.
+// This is called by main.main(). It only needs to happen once to the rootCmd.
+func Execute() {
+	err := rootCmd.Execute()
+	if err != nil {
+		os.Exit(1)
+	}
+}
+
+func init() {
+	cobra.OnInitialize()
+}