refactor: restructure API, deduplicate code, expand test coverage

- Extract shared DeferClose helper, removing 14 duplicate copies
- Rename PlayWright-prefixed types to cleaner names (BrowserOptions,
  BrowserSelection, NewBrowser, etc.)
- Rename fields: ServerAddress, RequireServer (was DontLaunchOnConnectFailure)
- Extract shared initBrowser/mergeOptions into browser_init.go,
  deduplicating ~120 lines between NewBrowser and NewInteractiveBrowser
- Remove unused locator field from document struct
- Add tests for all previously untested packages (archive, aislegopher,
  wegmans, useragents, powerball) and expand existing test suites
- Add MIGRATION.md documenting all breaking API changes

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

sites/google/cmd/google/main.go

@@ -3,12 +3,12 @@ package main
 import (
 	"context"
 	"fmt"
-	"io"
 	"os"
 	"strings"
 
 	"github.com/urfave/cli/v3"
 
+	"gitea.stevedudenhoeffer.com/steve/go-extractor"
 	"gitea.stevedudenhoeffer.com/steve/go-extractor/cmd/browser/pkg/browser"
 	"gitea.stevedudenhoeffer.com/steve/go-extractor/sites/google"
 )
@@ -42,12 +42,6 @@ func (f GoogleFlags) ToConfig(_ context.Context, cmd *cli.Command) google.Config
 	return c
 }
 
-func deferClose(cl io.Closer) {
-	if cl != nil {
-		_ = cl.Close()
-	}
-}
-
 func main() {
 	var flags []cli.Flag
 
@@ -67,7 +61,7 @@ func main() {
 
 			b, err := browser.FromCommand(ctx, cli)
 
-			defer deferClose(b)
+			defer extractor.DeferClose(b)
 
 			if err != nil {
 				return err