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/megamillions/megamillions_test.go

@@ -41,3 +41,33 @@ func TestNetTicksToTime_DifferenceIsCorrect(t *testing.T) {
 		t.Errorf("expected 1 second difference, got %v", diff)
 	}
 }
+
+func TestNetTicksToTime_NotZero(t *testing.T) {
+	// Verify the function produces a non-zero time for typical ticks values.
+	ticks := int64(638396256000000000)
+	result := netTicksToTime(ticks)
+
+	if result.IsZero() {
+		t.Error("netTicksToTime should not return zero time for valid ticks")
+	}
+}
+
+func TestConfig_Validate(t *testing.T) {
+	c := Config{}
+	c = c.validate()
+	_ = c // validate is a no-op, just verify no panic
+}
+
+func TestDrawing_ZeroValue(t *testing.T) {
+	var d Drawing
+	if d.MegaBall != 0 || d.Megaplier != 0 {
+		t.Error("zero-value Drawing should have zero fields")
+	}
+}
+
+func TestNextDrawing_ZeroValue(t *testing.T) {
+	var nd NextDrawing
+	if nd.Date != "" {
+		t.Error("zero-value NextDrawing should have empty date")
+	}
+}