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/hooks/useServerTTS.ts

@@ -134,14 +134,11 @@ export function useServerTTS(options: UseServerTTSOptions = {}): UseServerTTSRet
   const audioSourceRef = useRef<AudioBufferSourceNode | null>(null);
   const abortControllerRef = useRef<AbortController | null>(null);
   
-  // Get current model, threshold, and max length from config store for summarization
+  // Get current model and API settings from config store.
   const currentProviderId = useConfigStore((state) => state.currentProviderId);
   const currentModelId = useConfigStore((state) => state.currentModelId);
-  const summarizeCharacterThreshold = useConfigStore((state) => state.summarizeCharacterThreshold);
-  const summarizeMaxLength = useConfigStore((state) => state.summarizeMaxLength);
   const openaiApiKey = useConfigStore((state) => state.openaiApiKey);
   const openaiCompatibleUrl = useConfigStore((state) => state.openaiCompatibleUrl);
-  const settingsZenModel = useConfigStore((state) => state.settingsZenModel);
 
   // Check if server TTS is available
   const checkAvailability = useCallback(async (): Promise<boolean> => {
@@ -275,19 +272,14 @@ export function useServerTTS(options: UseServerTTSOptions = {}): UseServerTTSRet
           model: options?.model || undefined,
           speed: options?.speed || 0.9,
           instructions: options?.instructions,
-          summarize: options?.summarize ?? true, // Summarize by default for voice output
+          summarize: false,
           // Use provided provider/model, or fall back to current chat model
           providerId: options?.providerId || currentProviderId || undefined,
           modelId: options?.modelId || currentModelId || undefined,
-          // Use provided threshold, or fall back to user setting, or default to 200
-          threshold: options?.threshold ?? summarizeCharacterThreshold ?? 200,
-          // Max character length for summaries
-          maxLength: summarizeMaxLength ?? 500,
           // Send API key from settings if available
           apiKey: openaiApiKey || undefined,
           // Send custom base URL for OpenAI-compatible servers
           baseURL: options?.baseURL || undefined,
-          ...(settingsZenModel ? { zenModel: settingsZenModel } : {}),
         }),
         signal: abortControllerRef.current.signal,
       });
@@ -350,7 +342,7 @@ export function useServerTTS(options: UseServerTTSOptions = {}): UseServerTTSRet
       options?.onError?.(errorMsg);
       setIsPlaying(false);
     }
-  }, [stop, currentProviderId, currentModelId, summarizeCharacterThreshold, summarizeMaxLength, openaiApiKey, settingsZenModel]);
+  }, [stop, currentProviderId, currentModelId, openaiApiKey]);
 
   // Cleanup on unmount
   useEffect(() => {