Fix feed playback speed label refresh (#8623)

### Description
Fixes the per-podcast playback speed settings dialog so the numeric
speed value is shown immediately when the dialog is opened again.

Previously, the slider position was restored correctly, but the adjacent
numeric label could disappear after reopening the feed settings screen.
The dialog now refreshes the displayed speed label on initialization,
keeping the UI state consistent.



### Checklist
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app/src/main/java/de/danoeh/antennapod/ui/screen/feed/preferences/FeedSettingsPreferenceFragment.java

@@ -416,10 +416,11 @@ public class FeedSettingsPreferenceFragment extends PreferenceFragmentCompat {
             viewBinding.skipSilenceFeed.setAlpha(isChecked ? 0.4f : 1f);
         });
         float speed = feedPreferences.getFeedPlaybackSpeed();
-        FeedPreferences.SkipSilence skipSilence = feedPreferences.getFeedSkipSilence();
         boolean isGlobal = speed == FeedPreferences.SPEED_USE_GLOBAL;
         viewBinding.useGlobalCheckbox.setChecked(isGlobal);
         viewBinding.seekBar.updateSpeed(isGlobal ? 1 : speed);
+        viewBinding.currentSpeedLabel.setText(String.format(Locale.getDefault(), "%.2fx", isGlobal ? 1 : speed));
+        FeedPreferences.SkipSilence skipSilence = feedPreferences.getFeedSkipSilence();
         viewBinding.skipSilenceFeed.setChecked(!isGlobal
                 && skipSilence == FeedPreferences.SkipSilence.AGGRESSIVE);
         new MaterialAlertDialogBuilder(getContext())