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>

node_test.go

@@ -0,0 +1,23 @@
+package extractor
+
+import "testing"
+
+func TestEscapeJavaScript(t *testing.T) {
+	tests := []struct {
+		input string
+		want  string
+	}{
+		{"hello", "hello"},
+		{"it's", "it\\'s"},
+		{`back\slash`, `back\\slash`},
+		{`both\'`, `both\\\'`},
+		{"", ""},
+	}
+
+	for _, tt := range tests {
+		got := escapeJavaScript(tt.input)
+		if got != tt.want {
+			t.Errorf("escapeJavaScript(%q) = %q, want %q", tt.input, got, tt.want)
+		}
+	}
+}