feat: Add --args flag for natural language executor instructions (gt-1py3y)

- Add Args field to SlungWork struct in wisp/types.go
- Add --args/-a flag to gt sling command
- Display args in gt prime autonomous mode
- Display args in gt mol status output

The --args string is stored in the hook and shown to the LLM executor,
which interprets the instructions naturally without schema maintenance.

Example: gt sling beads-release --args "patch release"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

internal/cmd/molecule_status.go

@@ -462,6 +462,9 @@ func outputMoleculeStatus(status MoleculeStatusInfo) error {
 		if status.SlungWork.Context != "" {
 			fmt.Printf("   Context: %s\n", status.SlungWork.Context)
 		}
+		if status.SlungWork.Args != "" {
+			fmt.Printf("   Args: %s\n", style.Bold.Render(status.SlungWork.Args))
+		}
 		fmt.Printf("   Slung by: %s at %s\n",
 			status.SlungWork.CreatedBy,
 			status.SlungWork.CreatedAt.Format("2006-01-02 15:04:05"))