feat(v0.3): add --projects flag to ctask list

ctask list shows tasks by default and projects with --projects.
--all controls archived visibility (independent of --projects),
so the four combinations work as the spec defines:
  - ctask list                  active tasks
  - ctask list --all            active + archived tasks
  - ctask list --projects       active projects
  - ctask list --projects --all active + archived projects

Empty-result message reflects the active filter.

cmd/list.go

@@ -23,10 +23,12 @@ var (
 	listAll      bool
 	listCategory string
 	listLimit    int
+	listProjects bool
 )
 
 func init() {
 	listCmd.Flags().BoolVarP(&listAll, "all", "a", false, "Include archived workspaces")
+	listCmd.Flags().BoolVar(&listProjects, "projects", false, "Show projects instead of tasks")
 	listCmd.Flags().StringVarP(&listCategory, "category", "c", "", "Filter by category")
 	listCmd.Flags().IntVarP(&listLimit, "limit", "n", 20, "Maximum entries to show")
 	rootCmd.AddCommand(listCmd)
@@ -39,13 +41,18 @@ func runList(cmd *cobra.Command, args []string) error {
 		IncludeArchived: listAll,
 		Category:        listCategory,
 		Limit:           listLimit,
+		Projects:        listProjects,
 	})
 	if err != nil {
 		return err
 	}
 
 	if len(results) == 0 {
-		fmt.Println("No workspaces found.")
+		if listProjects {
+			fmt.Println("No projects found.")
+		} else {
+			fmt.Println("No tasks found.")
+		}
 		return nil
 	}