refactor: move V1 code into v1/ subdirectory

- git mv cmd/ internal/ pkg/ test/ go.mod go.sum Makefile build.sh docs/ v1/
- Create v1/README.md with V1 documentation
- Update root README for V1 + V2 structure
- V1 still builds (cd v1 && go build ./cmd/hostkeeper) and 105 tests pass
- Root is now clean for V2 development

v1/cmd/hostkeeper/tui.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"context"
+	"fmt"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/spf13/cobra"
+
+	"git.tukangketik.id/swanadiva/hostkeeper/pkg/config"
+	"git.tukangketik.id/swanadiva/hostkeeper/pkg/knownhosts"
+	"git.tukangketik.id/swanadiva/hostkeeper/pkg/storage"
+	"git.tukangketik.id/swanadiva/hostkeeper/pkg/tui"
+)
+
+var encryptFlag bool
+
+// tuiCmd represents the tui command
+var tuiCmd = &cobra.Command{
+	Use:   "tui",
+	Short: "Launch terminal user interface",
+	Long:  `Launch an interactive terminal user interface for managing SSH hosts and connections.`,
+	RunE:  runTUI,
+}
+
+func init() {
+	rootCmd.AddCommand(tuiCmd)
+	tuiCmd.Flags().BoolVar(&encryptFlag, "encrypt", false, "Enable AES-256-GCM encryption for sensitive data")
+}
+
+func runTUI(cmd *cobra.Command, args []string) error {
+	cfg := appCfg
+	if cfg == nil {
+		var err error
+		cfg, err = config.New()
+		if err != nil {
+			return fmt.Errorf("failed to initialize config: %w", err)
+		}
+	}
+
+	store, err := storage.NewJSONStorage(cfg.GetDataDir())
+	if err != nil {
+		return fmt.Errorf("failed to initialize storage: %w", err)
+	}
+
+	// Initialize known_hosts
+	kh, err := knownhosts.New(cfg.GetDataDir())
+	if err != nil {
+		fmt.Printf("Warning: failed to load known_hosts: %v\n", err)
+	}
+
+	// Auto-detect encrypted data files
+	needPassword := encryptFlag || store.IsDataEncrypted()
+
+	model := tui.New()
+	model.SetDataDir(cfg.GetDataDir())
+	if kh != nil {
+		model.SetKnownHosts(kh)
+	}
+
+	if needPassword {
+		// Show password prompt first — hosts will be loaded after password is set
+		model.ShowEncryptPrompt()
+	} else {
+		// No encryption — load hosts normally
+		ctx := context.Background()
+		hosts, err := store.ListHosts(ctx)
+		if err != nil {
+			return fmt.Errorf("failed to load hosts: %w", err)
+		}
+		model.LoadHosts(hosts)
+	}
+
+	p := tea.NewProgram(model)
+	model.SetProgram(p)
+	if _, err := p.Run(); err != nil {
+		return fmt.Errorf("failed to run TUI: %w", err)
+	}
+
+	return nil
+}