refactor(text): extract shared summarization service with tts/note/notification modes

Move server-side summarization out of lib/tts/summarization.js into a shared
lib/text module exposing tts, note and notification modes. TTS and notification
runtimes now delegate to the shared service, note mode is used to distill a
selected excerpt into a short project note. Expose the new endpoint via
/api/text/summarize and route it through the common request middleware.

Client voice/summarize.ts accepts a mode option and points at the new
endpoint with an absolute URL that respects the desktop server origin.
VS Code webview swaps the stubbed tts summarize path for /api/text/summarize
and hardens URL parsing with window.location.href as the base.

packages/ui/src/lib/voice/summarize.ts

@@ -1,12 +1,24 @@
 /**
- * Text summarization utility for TTS
+ * Text summarization utility
  * 
- * Calls the server-side summarization endpoint which uses
+ * Calls the server-side text summarization endpoint which uses
  * the opencode.ai zen API with gpt-5-nano.
  */
 
 import { useConfigStore } from '@/stores/useConfigStore';
 
+const resolveSummarizeUrl = (): string => {
+    if (typeof window === 'undefined') {
+        return '/api/text/summarize';
+    }
+
+    const desktopServer = (window as typeof window & {
+        __OPENCHAMBER_DESKTOP_SERVER__?: { origin: string };
+    }).__OPENCHAMBER_DESKTOP_SERVER__;
+    const baseOrigin = desktopServer?.origin || window.location.origin;
+    return new URL('/api/text/summarize', baseOrigin).toString();
+};
+
 /**
  * Summarize text using the server-side zen API endpoint
  * 
@@ -21,25 +33,32 @@ export async function summarizeText(
         threshold?: number;
         /** Max characters for the summary output */
         maxLength?: number;
+        /** Summarization mode */
+        mode?: 'tts' | 'note';
     }
 ): Promise<string> {
     const store = useConfigStore.getState();
     const threshold = options?.threshold ?? store.summarizeCharacterThreshold;
     const maxLength = options?.maxLength ?? store.summarizeMaxLength;
+    const mode = options?.mode ?? 'tts';
+    const normalizedSource = text.replace(/\s+/g, ' ').trim();
     
     // Don't summarize if text is under threshold
     if (text.length <= threshold) {
+        if (mode === 'note') {
+            throw new Error('Note summarization threshold bypass is not allowed');
+        }
         return text;
     }
     
     try {
         const zenModel = store.settingsZenModel;
-        const response = await fetch('/api/tts/summarize', {
+         const response = await fetch(resolveSummarizeUrl(), {
             method: 'POST',
             headers: {
                 'Content-Type': 'application/json',
             },
-            body: JSON.stringify({ text, threshold, maxLength, ...(zenModel ? { zenModel } : {}) }),
+             body: JSON.stringify({ text, threshold, maxLength, mode, ...(zenModel ? { zenModel } : {}) }),
         });
         
         if (!response.ok) {
@@ -56,14 +75,27 @@ export async function summarizeText(
             summaryLength?: number;
         };
         
-        if (data.summarized && data.summary) {
-            return data.summary;
+        if (typeof data.summary === 'string' && data.summary.trim().length > 0) {
+            const summary = data.summary.trim();
+            if (mode === 'note') {
+                const normalizedSummary = summary.replace(/\s+/g, ' ').trim();
+                if (normalizedSummary === normalizedSource) {
+                    throw new Error('Note distillation returned source text unchanged');
+                }
+            }
+            return summary;
         }
         
-        // Return original text if not summarized
+        if (mode === 'note') {
+            throw new Error('Note summarization returned no distilled result');
+        }
+        // Return original text if the server produced nothing usable
         return text;
     } catch (err) {
         console.error('[summarize] Failed to summarize:', err);
+        if (mode === 'note') {
+            throw err instanceof Error ? err : new Error('Note summarization failed');
+        }
         // Return original text on error
         return text;
     }