fix: use merged flags in archive cmd and move defer after error checks

- Fix archive cmd passing only archive-specific Flags instead of the
  merged flags variable that includes browser flags (#8)
- Move defer DeferClose() after error checks in 6 locations to prevent
  calling Close on nil values (#19):
  - sites/duckduckgo/cmd/duckduckgo/main.go
  - sites/duckduckgo/duckduckgo.go
  - sites/google/cmd/google/main.go
  - sites/wegmans/cmd/wegmans/main.go
  - sites/wegmans/wegmans.go
  - sites/aislegopher/aislegopher.go

Closes #8, #19

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

sites/archive/cmd/archive/main.go

@@ -56,7 +56,7 @@ func main() {
 	cli := &cli.Command{
 		Name:  "archive",
 		Usage: "Archive a website",
-		Flags: Flags,
+		Flags: flags,
 		Action: func(ctx context.Context, cli *cli.Command) error {
 
 			target := cli.Args().First()