feat: brainstorm sessions, PDF document Q&A, embedding fixes, and UI improvements

- Add brainstorm feature with collaborative canvas, AI idea generation, live cursors, playback, and export
- Add PDF upload/extraction/ingestion pipeline with pgvector document search (RAG)
- Add document Q&A overlay with streaming chat and PDF preview
- Add note attachments UI with status polling, grid layout, and auto-scroll
- Add task extraction AI tool and agent executor improvements
- Fix NoteEmbedding missing updatedAt column, re-index 66 notes with 1536-dim embeddings
- Fix brainstorm 'Create Note' button: add success toast and redirect to created note
- Fix memory echo notification infinite polling
- Fix chat route to always include document_search tool
- Add brainstorm i18n keys across all 14 locales
- Add socket server for real-time brainstorm collaboration
- Add hierarchical notebook selector and organize notebook dialog improvements
- Add sidebar brainstorm section with session management
- Update prisma schema with brainstorm tables, attachments, and document chunks

memento-note/components/note-editor/note-title-block.tsx

@@ -61,7 +61,7 @@ export function NoteTitleBlock() {
                 const plain = state.content.replace(/<[^>]+>/g, ' ').trim()
                 const wordCount = plain.split(/\s+/).filter(Boolean).length
                 if (wordCount < 10) {
-                  toast.error('Ajoutez au moins 10 mots avant de générer un titre.')
+                  toast.error(t('ai.titleGenerationMinWords', { count: wordCount }))
                   return
                 }
                 actions.setIsProcessingAI(true)
@@ -76,20 +76,20 @@ export function NoteTitleBlock() {
                     const s = data.suggestions?.[0]?.title ?? ''
                     if (s) {
                       actions.setTitle(s)
-                      toast.success('Titre généré !')
+                      toast.success(t('ai.titleApplied'))
                     } else {
-                      toast.error('Impossible de générer un titre.')
+                      toast.error(t('ai.titleGenerationFailed'))
                     }
                   } else {
-                    toast.error('Erreur lors de la génération du titre.')
+                    toast.error(t('ai.titleGenerationError'))
                   }
                 } catch (e) {
-                  toast.error('Erreur réseau.')
+                  toast.error(t('ai.networkErrorShort'))
                 } finally { actions.setIsProcessingAI(false) }
               }}
               disabled={state.isProcessingAI}
               className="absolute right-0 top-2 opacity-0 group-hover:opacity-60 hover:!opacity-100 transition-opacity rounded-lg p-2 text-foreground/50 hover:bg-black/5"
-              title="Générer un titre automatique avec l'IA"
+              title={t('ai.generateTitlesTooltip')}
             >
               {state.isProcessingAI ? <Loader2 className="h-5 w-5 animate-spin" /> : <Sparkles className="h-5 w-5" />}
             </button>