feat(dashboard): tableau de bord Second Brain configurable avec chargement progressif

Briefing granulaire, pistes rapides puis enrichissement async, layout persisté v5,
suggestions agents, intégration Gmail et navigation sidebar alignée sur /home.

Co-authored-by: Cursor <cursoragent@cursor.com>

memento-note/lib/ai/services/memory-echo.service.ts

@@ -10,6 +10,12 @@ import {
   prepareNoteTextForEmbedding,
 } from '@/lib/text/plain-text'
 import { detectTextDirection } from '@/lib/clip/rtl-content'
+import { detectUserLanguage } from '@/lib/i18n/detect-user-language'
+import type { SupportedLanguage } from '@/lib/i18n/load-translations'
+import {
+  buildMemoryEchoInsightPrompt,
+  getMemoryEchoInsightFallback,
+} from '@/lib/ai/memory-echo-i18n'
 import {
   SEMANTIC_SIMILARITY_FLOOR_CLIP,
   SEMANTIC_SIMILARITY_FLOOR_DEMO,
@@ -334,38 +340,16 @@ export class MemoryEchoService {
     note1Title: string | null,
     note1Content: string,
     note2Title: string | null,
-    note2Content: string
+    note2Content: string,
+    language: SupportedLanguage = 'en',
   ): Promise<string> {
     try {
       const config = await getSystemConfig()
       const provider = getChatProvider(config)
 
-      const note1Desc = note1Title || 'Untitled note'
-      const note2Desc = note2Title || 'Untitled note'
       const excerpt1 = excerptPlainNoteContent(note1Title, note1Content, 1200)
       const excerpt2 = excerptPlainNoteContent(note2Title, note2Content, 1200)
-      const directionSample = `${note1Desc}\n${excerpt1}\n${note2Desc}\n${excerpt2}`
-      const isRtl = detectTextDirection(directionSample) === 'rtl'
-
-      const prompt = isRtl
-        ? `تو یک دستیار هستی که ارتباط بین یادداشت‌ها را تحلیل می‌کنی.
-
-یادداشت ۱: «${note1Desc}»
-متن: ${excerpt1}
-
-یادداشت ۲: «${note2Desc}»
-متن: ${excerpt2}
-
-در یک جمله کوتاه (حداکثر ۱۵ کلمه) به فارسی توضیح بده چرا این دو یادداشت به هم مرتبط‌اند. فقط رابطه معنایی را بگو.`
-        : `You are a helpful assistant analyzing connections between notes.
-
-Note 1: "${note1Desc}"
-Content: ${excerpt1}
-
-Note 2: "${note2Desc}"
-Content: ${excerpt2}
-
-Explain in one brief sentence (max 15 words) why these notes are connected. Focus on the semantic relationship.`
+      const prompt = buildMemoryEchoInsightPrompt(language, note1Title, excerpt1, note2Title, excerpt2)
 
       const response = await provider.generateText(prompt)
 
@@ -375,20 +359,15 @@ Explain in one brief sentence (max 15 words) why these notes are connected. Focu
         .trim()
         .substring(0, 150)
 
-      const fallback = isRtl
-        ? 'این یادداشت‌ها از نظر معنایی به هم مرتبط به نظر می‌رسند.'
-        : 'These notes appear to be semantically related.'
-
-      return insight || fallback
+      return insight || getMemoryEchoInsightFallback(language)
 
     } catch (error) {
       console.error('[MemoryEcho] Failed to generate insight:', error)
       const sample = excerptPlainNoteContent(note1Title, note1Content, 200)
         + excerptPlainNoteContent(note2Title, note2Content, 200)
-      if (detectTextDirection(sample) === 'rtl') {
-        return 'این یادداشت‌ها از نظر معنایی به هم مرتبط به نظر می‌رسند.'
-      }
-      return 'These notes appear to be semantically related.'
+      const rtl = detectTextDirection(sample) === 'rtl'
+      if (rtl) return getMemoryEchoInsightFallback(language === 'fa' || language === 'ar' ? language : 'fa')
+      return getMemoryEchoInsightFallback(language)
     }
   }
 
@@ -484,12 +463,14 @@ Explain in one brief sentence (max 15 words) why these notes are connected. Focu
       return null // All connections already shown
     }
 
-    // Generate AI insight
+    // Generate AI insight in user's language
+    const userLanguage = await detectUserLanguage()
     const insightText = await this.generateInsight(
       newConnection.note1.title,
       newConnection.note1.content,
       newConnection.note2.title,
-      newConnection.note2.content || ''
+      newConnection.note2.content || '',
+      userLanguage,
     )
 
     // Store insight in database