fix(audit): sécurité + perf + DB — 40 problèmes adressés

SÉCURITÉ (CRITIQUE):
- link-preview: auth() obligatoire + filtre IP privées (SSRF fix)
- metrics: !metricsToken → 401 au lieu d'etre ouvert si token absent
- contextual-ai-chat: DOMPurify.sanitize() sur dangerouslySetInnerHTML (XSS fix)

PERFORMANCE:
- graph/route.ts: take:500 + orderBy updatedAt desc (pas de full table scan)
- syncAllEmbeddings: batch parallèle Promise.allSettled × 5 (pas séquentiel)
- 80 console.log supprimés du code production

BASE DE DONNÉES:
- Note: index contentUpdatedAt + isPublic ajoutés au schema
- DocumentChunk: commentaire index vectoriel HNSW (à exécuter manuellement)

memento-note/lib/ai/services/chart-suggestion.service.ts

@@ -52,7 +52,6 @@ function getCached(key: string): SuggestChartsResponse | null {
     cache.delete(key)
     return null
   }
-  console.log('[chart-suggestion] Cache hit for key:', key)
   return entry.data
 }
 
@@ -74,22 +73,18 @@ function setCached(key: string, data: SuggestChartsResponse): void {
 export async function suggestCharts(request: SuggestChartsRequest): Promise<SuggestChartsResponse> {
   // Check cache first
   const cacheKey = getCacheKey(request.content || '', request.selection)
-  console.log('[suggestCharts] Cache key:', cacheKey, 'contentLen:', request.content?.length, 'selectionLen:', request.selection?.length)
 
   const cached = getCached(cacheKey)
   if (cached) {
-    console.log('[suggestCharts] CACHE HIT - returning cached data')
     return cached
   }
 
-  console.log('[suggestCharts] CACHE MISS - trying fast parser first')
 
   // FAST PATH: Try regex parser first - NO AI call needed!
   const textToParse = request.selection || request.content || ''
   const parsed = parseChartData(textToParse)
 
   if (parsed.hasData && parsed.confidence > 0.3) {
-    console.log('[suggestCharts] FAST PATH - regex parser found data, skipping AI!')
     const suggestions = generateChartSuggestions(parsed.data)
 
     const response: SuggestChartsResponse = {
@@ -104,7 +99,6 @@ export async function suggestCharts(request: SuggestChartsRequest): Promise<Sugg
     return response
   }
 
-  console.log('[suggestCharts] Parser found no good data, calling AI API (slow...)')
 
   try {
     const response = await fetch('/api/ai/suggest-charts', {
@@ -135,9 +129,7 @@ export async function suggestCharts(request: SuggestChartsRequest): Promise<Sugg
     // Cache successful responses
     if (!data.error && !data.quotaExceeded) {
       setCached(cacheKey, data)
-      console.log('[suggestCharts] Cached response for key:', cacheKey, 'cache size now:', cache.size)
     } else {
-      console.log('[suggestCharts] NOT caching (has error or quota exceeded)')
     }
 
     return data