feat: all six CLI commands (new, list, resume, open, info, archive)

Complete command implementations with all flags per spec. Shared query resolution helper.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cmd/archive.go

@@ -0,0 +1,42 @@
+package cmd
+
+import (
+	"fmt"
+	"path/filepath"
+	"time"
+
+	"github.com/spf13/cobra"
+	"github.com/warrenronsiek/ctask/internal/config"
+	"github.com/warrenronsiek/ctask/internal/workspace"
+)
+
+var archiveCmd = &cobra.Command{
+	Use:   "archive <query>",
+	Short: "Mark a workspace as archived",
+	Args:  cobra.ExactArgs(1),
+	RunE:  runArchive,
+}
+
+func init() {
+	rootCmd.AddCommand(archiveCmd)
+}
+
+func runArchive(cmd *cobra.Command, args []string) error {
+	root := config.ResolveRoot()
+	ws := resolveOne(root, args[0], false)
+
+	now := time.Now().UTC().Truncate(time.Second)
+	ws.Meta.Status = "archived"
+	ws.Meta.ArchivedAt = &now
+	ws.Meta.UpdatedAt = now
+
+	metaPath := filepath.Join(ws.Path, "task.yaml")
+	if err := workspace.WriteMeta(metaPath, ws.Meta); err != nil {
+		return fmt.Errorf("updating metadata: %w", err)
+	}
+
+	relPath := workspace.RelativePath(root, ws.Path)
+	fmt.Printf("[ctask] archived: %s\n", relPath)
+
+	return nil
+}