Add dry-run flag and implement AUR support

cmd/declpac/main.go

@@ -17,6 +17,7 @@ import (
 type Config struct {
 	StateFiles []string
 	NoConfirm  bool
+	DryRun     bool
 }
 
 func main() {
@@ -38,6 +39,11 @@ func main() {
 				Usage:       "Skip confirmation prompts",
 				Destination: &cfg.NoConfirm,
 			},
+			&cli.BoolFlag{
+				Name:        "dry-run",
+				Usage:       "Simulate the sync without making changes",
+				Destination: &cfg.DryRun,
+			},
 		},
 		Action: func(ctx context.Context, cmd *cli.Command) error {
 			return run(cfg)
@@ -63,6 +69,16 @@ func run(cfg *Config) error {
 		return err
 	}
 
+	if cfg.DryRun {
+		result, err := pacman.DryRun(merged)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "error: %v\n", err)
+			return err
+		}
+		fmt.Println(output.Format(result))
+		return nil
+	}
+
 	result, err := pacman.Sync(merged)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "error: %v\n", err)