feat: auto-detect encrypted files + CLI --password flag

- Storage.IsDataEncrypted() checks if hosts.json is encrypted
- TUI auto-detects encrypted files, prompts password automatically
- Root command: --password flag for all CLI commands
- newStorage() helper applies password flag to storage
- add/list/edit/delete commands now support encrypted storage
- passwordSetMsg loads hosts after password is set

cmd/hostkeeper/edit.go

@@ -75,7 +75,7 @@ func runEditHost(cmd *cobra.Command, args []string) error {
 		}
 	}
 
-	store, err := storage.NewJSONStorage(cfg.GetDataDir())
+	store, err := newStorage(cfg)
 	if err != nil {
 		return fmt.Errorf("failed to initialize storage: %w", err)
 	}