chore: retire zen-backed summarization

Disable the active Zen summarization flow because the unauthenticated/free Zen provider is no longer available and now returns usage-limit errors for this feature.

Keep /api/text/summarize as an API-compatible stub that returns local sanitized or distilled fallback text with summarized=false, rather than attempting external model calls.

Remove notification and voice playback summary behavior from runtime paths. Notification {last_message} now always uses normalized truncated text, and TTS playback ignores historical summarize request fields.

Hide the notification summary settings and voice summarize-before-playback controls while preserving legacy persisted settings for compatibility. Also disable Zen model startup validation and make Zen model list routes return empty results.

Update module documentation and tests to describe the retired provider behavior and the remaining compatibility stubs.

packages/ui/src/lib/i18n/messages/en.settings.ts

@@ -1302,7 +1302,7 @@ export const settingsDict = {
   'settings.notifications.page.testNotification.body': 'This is a test notification from OpenChamber.',
   'settings.voice.page.section.voiceSetup': 'Voice Setup',
   'settings.voice.page.section.speechRecognition': 'Speech Recognition',
-  'settings.voice.page.section.playbackAndSummary': 'Playback & Summarization',
+  'settings.voice.page.section.playbackAndSummary': 'Playback',
   'settings.voice.page.field.enableVoiceModeAria': 'Enable voice mode',
   'settings.voice.page.field.enableVoiceMode': 'Enable Voice Mode',
   'settings.voice.page.field.provider': 'Provider',

packages/ui/src/lib/i18n/messages/es.settings.ts

@@ -1302,7 +1302,7 @@ export const settingsDict = {
   "settings.notifications.page.testNotification.body": "Esta es una notificación de prueba de OpenChamber.",
   "settings.voice.page.section.voiceSetup": "Configuración de voz",
   "settings.voice.page.section.speechRecognition": "Reconocimiento de voz",
-  "settings.voice.page.section.playbackAndSummary": "Reproducción y resumen",
+  "settings.voice.page.section.playbackAndSummary": "Reproducción",
   "settings.voice.page.field.enableVoiceModeAria": "Habilitar modo de voz",
   "settings.voice.page.field.enableVoiceMode": "Habilitar modo de voz",
   "settings.voice.page.field.provider": "Proveedor",

packages/ui/src/lib/i18n/messages/ko.settings.ts

@@ -1302,7 +1302,7 @@ export const settingsDict = {
   'settings.notifications.page.testNotification.body': 'OpenChamber의 테스트 알림입니다.',
   'settings.voice.page.section.voiceSetup': '음성',
   'settings.voice.page.section.speechRecognition': '음성 인식',
-  'settings.voice.page.section.playbackAndSummary': '재생 및 요약',
+  'settings.voice.page.section.playbackAndSummary': '재생',
   'settings.voice.page.field.enableVoiceModeAria': '음성 모드 활성화',
   'settings.voice.page.field.enableVoiceMode': '음성 모드 활성화',
   'settings.voice.page.field.provider': '프로바이더',

packages/ui/src/lib/i18n/messages/pl.settings.ts

@@ -1548,7 +1548,7 @@ export const settingsDict = {
   'settings.voice.page.stt.wasmNotLoaded': 'Model zostanie pobrany przy pierwszym użyciu',
   'settings.voice.page.stt.wasmDownload': 'Pobierz',
   'settings.voice.page.stt.wasmRetry': 'Spróbuj ponownie',
-  'settings.voice.page.section.playbackAndSummary': 'Odtwarzanie i podsumowanie',
+  'settings.voice.page.section.playbackAndSummary': 'Odtwarzanie',
   'settings.voice.page.section.speechRecognition': 'Rozpoznawanie mowy',
   'settings.voice.page.section.voiceSetup': 'Konfiguracja głosu',
   'settings.voice.page.tooltip.browser': 'Darmowe, offline, ograniczone wsparcie mobilne.',

packages/ui/src/lib/i18n/messages/pt-BR.settings.ts

@@ -1302,7 +1302,7 @@ export const settingsDict = {
   "settings.notifications.page.testNotification.body": "Esta é uma notificação de teste do OpenChamber.",
   "settings.voice.page.section.voiceSetup": "Configurações de voz",
   "settings.voice.page.section.speechRecognition": "Reconhecimento de voz",
-  "settings.voice.page.section.playbackAndSummary": "Reprodução e resumo",
+  "settings.voice.page.section.playbackAndSummary": "Reprodução",
   "settings.voice.page.field.enableVoiceModeAria": "Ativar modo de voz",
   "settings.voice.page.field.enableVoiceMode": "Ativar modo de voz",
   "settings.voice.page.field.provider": "Provedor",

packages/ui/src/lib/i18n/messages/uk.settings.ts

@@ -1302,7 +1302,7 @@ export const settingsDict = {
   "settings.notifications.page.testNotification.body": "Це тестове сповіщення від OpenChamber.",
   "settings.voice.page.section.voiceSetup": "Налаштування голосу",
   "settings.voice.page.section.speechRecognition": "Розпізнавання мовлення",
-  "settings.voice.page.section.playbackAndSummary": "Відтворення та підсумовування",
+  "settings.voice.page.section.playbackAndSummary": "Відтворення",
   "settings.voice.page.field.enableVoiceModeAria": "Увімкнути голосовий режим",
   "settings.voice.page.field.enableVoiceMode": "Увімкнути голосовий режим",
   "settings.voice.page.field.provider": "Провайдер",

packages/ui/src/lib/i18n/messages/zh-CN.settings.ts

@@ -1302,7 +1302,7 @@ export const settingsDict = {
   'settings.notifications.page.testNotification.body': '这是来自 OpenChamber 的测试通知。',
   'settings.voice.page.section.voiceSetup': '语音设置',
   'settings.voice.page.section.speechRecognition': '语音识别',
-  'settings.voice.page.section.playbackAndSummary': '播放与摘要',
+  'settings.voice.page.section.playbackAndSummary': '播放',
   'settings.voice.page.field.enableVoiceModeAria': '启用语音模式',
   'settings.voice.page.field.enableVoiceMode': '启用语音模式',
   'settings.voice.page.field.provider': '提供方',