feat(cmd): add gt goals command skeleton

Create goals.go with basic command structure for viewing strategic
goals (epics) with staleness indicators. Includes --json, --status,
and --priority flags. Implementation stubs return not-yet-implemented
errors.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/goals.go

@@ -0,0 +1,60 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+// Goal command flags
+var (
+	goalsJSON     bool
+	goalsStatus   string
+	goalsPriority string
+)
+
+var goalsCmd = &cobra.Command{
+	Use:     "goals [goal-id]",
+	GroupID: GroupWork,
+	Short:   "View strategic goals (epics) with staleness indicators",
+	Long: `View strategic goals (epics) across the workspace.
+
+Goals are high-level objectives that organize related work items.
+This command shows goals with staleness indicators to help identify
+stale or neglected strategic initiatives.
+
+Examples:
+  gt goals              # List all open goals
+  gt goals --json       # Output as JSON
+  gt goals --status=all # Show all goals including closed
+  gt goals hq-abc       # Show details for a specific goal`,
+	RunE: runGoals,
+}
+
+func init() {
+	goalsCmd.Flags().BoolVar(&goalsJSON, "json", false, "Output as JSON")
+	goalsCmd.Flags().StringVar(&goalsStatus, "status", "open", "Filter by status (open, closed, all)")
+	goalsCmd.Flags().StringVar(&goalsPriority, "priority", "", "Filter by priority (e.g., P0, P1, P2)")
+	rootCmd.AddCommand(goalsCmd)
+}
+
+func runGoals(cmd *cobra.Command, args []string) error {
+	// If arg provided, show specific goal
+	if len(args) > 0 {
+		goalID := args[0]
+		return showGoal(goalID)
+	}
+
+	// Otherwise list all goals
+	return listGoals()
+}
+
+func showGoal(goalID string) error {
+	// TODO: Implement goal details view
+	return fmt.Errorf("goal details not yet implemented: %s", goalID)
+}
+
+func listGoals() error {
+	// TODO: Implement goals listing with staleness
+	return fmt.Errorf("goals listing not yet implemented")
+}