wrapper: default new users to English audio + subs (was pol/eng)

Owner flipped libraries to PreferredMetadataLanguage=en, MetadataCountryCode=US.
New-user defaults must match. Wrapper now sets:
  AudioLanguagePreference=eng (was pol)
  SubtitleLanguagePreference=eng
  SubtitleMode=Default (was Always — let player decide based on audio)

bin/add-jellyfin-user.sh

@@ -66,15 +66,16 @@ rm -f /tmp/dp-cur.$$.json /tmp/dp-fix.$$.json
 [[ "$HTTP" == "204" ]] || { echo "  DisplayPreferences POST failed: $HTTP"; exit 1; }
 echo "  Home layout applied."
 
-echo "[3/3] Setting subtitle + audio prefs (subs=Always/eng, audio=pol)..."
+echo "[3/3] Setting language prefs (audio=eng, subs=eng default)..."
 curl -ks "$JELLYFIN_URL/Users/$USER_ID" -H "Authorization: $AUTH" > /tmp/u.$$.json
 python3 - <<EOF > /tmp/u-fix.$$.json
 import json
 with open('/tmp/u.$$.json') as f: u = json.load(f)
 c = u['Configuration']
-c['SubtitleMode'] = 'Always'
+c['SubtitleMode'] = 'Default'
 c['SubtitleLanguagePreference'] = 'eng'
-c['AudioLanguagePreference'] = 'pol'
+c['AudioLanguagePreference'] = 'eng'
+c['PlayDefaultAudioTrack'] = True
 print(json.dumps(c))
 EOF
 HTTP=$(curl -ks -X POST "$JELLYFIN_URL/Users/$USER_ID/Configuration" \