feat: bloc Toggle/Section repliable + infrastructure embeddings par fragments

- Nouveau bloc Toggle : sections dépliables dans l'éditeur (slash menu + drag handle)
  - Transformer un bloc existant en section repliable via le menu d'action
  - Boutons désactiver (unwrap) et supprimer dans l'en-tête
  - i18n FR/EN complet
- Infrastructure embeddings par fragments (inspiré AppFlowy)
  - Table NoteEmbeddingChunk + index HNSW
  - Chunking sémantique (~1000 chars, overlap 200, dedup par hash)
  - Indexation incrémentale au save (createNote + updateNote + clip)
  - Queue concurrence 4, retry backoff exponentiel

memento-note/app/actions/notes.ts

@@ -8,6 +8,7 @@ import { getAIProvider } from '@/lib/ai/factory'
 import { parseNote, getHashColor } from '@/lib/utils'
 import { upsertNoteEmbedding } from '@/lib/embeddings'
 import { embeddingService } from '@/lib/ai/services/embedding.service'
+import { chunkIndexingService } from '@/lib/ai/services/chunk-indexing.service'
 import { syncNoteLinksForNote } from '@/lib/notes/sync-note-links'
 import { getSystemConfig, getConfigNumber, getConfigBoolean, SEARCH_DEFAULTS } from '@/lib/config'
 import { contextualAutoTagService } from '@/lib/ai/services/contextual-auto-tag.service'
@@ -458,6 +459,12 @@ export async function createNote(data: {
           console.error('[BG] Embedding generation failed:', e)
         }
 
+        try {
+          await chunkIndexingService.indexNote(noteId, data.title, content)
+        } catch (e) {
+          console.error('[BG] Chunk indexing failed:', e)
+        }
+
         // Background task 2: Auto-labeling (only if no user labels and has notebook)
         if (!hasUserLabels && notebookId) {
           try {
@@ -596,6 +603,12 @@ export async function updateNote(id: string, data: {
         } catch (e) {
           console.error('[BG] Embedding regeneration failed:', e);
         }
+
+        try {
+          await chunkIndexingService.indexNote(noteId, title, content);
+        } catch (e) {
+          console.error('[BG] Chunk indexing failed:', e);
+        }
       })();
     }