feat(v0.5.2): direct lookup includes archived; resume hint for archived

Apply the v0.5.2 lookup policy to the existing commands and wire
ValidArgsFunction hooks across the workspace-accepting surface.

info: drop the --all/-a flag entirely. Direct lookup is now
archived-inclusive by default — the user typed a name, so we find
the workspace and surface its status in the output. The Status
line already distinguishes active vs archived clearly.

resume: when targeting an archived workspace, fail with a useful
hint instead of letting the resolver report "not found":

  [ctask] error: workspace "X" is archived

  To restore it:
    ctask restore X

This is implemented by resolving archived-inclusive and rejecting
status==archived before any session-launch logic runs. Genuine
not-found and ambiguous-match behavior are unchanged.

Adds ValidArgsFunction hooks to archive (active), delete (active),
open (active), info (any), resume (active). Restore/notes/path
already have hooks from the previous commit. Shell completion now
covers the full direct-lookup surface.

cmd/resume_test.go

@@ -0,0 +1,80 @@
+package cmd
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/warrenronsiek/ctask/internal/workspace"
+)
+
+// callDoResumeArchived is a focused harness: it sets CTASK_ROOT, captures
+// stderr, and runs doResume. The test fixtures only exercise the early
+// archived-status branch; we never reach session.Run because the archived
+// branch returns first.
+func callDoResumeArchived(t *testing.T, root, query string) (stderr string, err error) {
+	t.Helper()
+
+	prevRoot := os.Getenv("CTASK_ROOT")
+	os.Setenv("CTASK_ROOT", root)
+	defer func() {
+		if prevRoot == "" {
+			os.Unsetenv("CTASK_ROOT")
+		} else {
+			os.Setenv("CTASK_ROOT", prevRoot)
+		}
+	}()
+
+	errR, errW, _ := os.Pipe()
+	prevStderr := os.Stderr
+	os.Stderr = errW
+	defer func() { os.Stderr = prevStderr }()
+
+	err = doResume(query, false, false, false, "")
+	errW.Close()
+	var buf bytes.Buffer
+	buf.ReadFrom(errR)
+	return buf.String(), err
+}
+
+func TestResumeArchivedWorkspaceShowsRestoreHint(t *testing.T) {
+	root := t.TempDir()
+	wsDir := filepath.Join(root, "general", "2026-04-22_resume-archived")
+	os.MkdirAll(wsDir, 0755)
+	now := time.Now().UTC().Truncate(time.Second)
+	archived := now.Add(-time.Hour)
+	meta := &workspace.TaskMeta{
+		ID: "t", Slug: "resume-archived", Title: "resume-archived",
+		CreatedAt: now, UpdatedAt: archived,
+		ArchivedAt: &archived,
+		Status:     "archived",
+		Category:   "general",
+		Type:       "task",
+		Mode:       "local",
+		Agent:      "claude",
+	}
+	workspace.WriteMeta(filepath.Join(wsDir, "task.yaml"), meta)
+
+	stderr, err := callDoResumeArchived(t, root, "resume-archived")
+	if err == nil {
+		t.Fatal("expected error resuming archived workspace")
+	}
+	if !strings.Contains(stderr, `workspace "resume-archived" is archived`) {
+		t.Errorf("stderr should explain archived state: %q", stderr)
+	}
+	if !strings.Contains(stderr, "ctask restore resume-archived") {
+		t.Errorf("stderr should contain restore hint: %q", stderr)
+	}
+
+	// Workspace metadata must be unchanged (no UpdatedAt bump).
+	got, _ := workspace.ReadMeta(filepath.Join(wsDir, "task.yaml"))
+	if got.Status != "archived" {
+		t.Errorf("workspace mutated despite refusal: status=%s", got.Status)
+	}
+	if !got.UpdatedAt.Equal(archived) {
+		t.Errorf("UpdatedAt advanced despite refusal: was %v, now %v", archived, got.UpdatedAt)
+	}
+}