feat: collaboration temps reel - edition simultanee (#62)

WebSocket /ws/collab/{vault}/{path} (rooms par fichier), relais Yjs/CRDT, awareness (curseurs colores + presence), persistance serveur debounce 2s, auth WS + check_vault_access, reconnexion automatique. Frontend frontend/js/collab.js, backend backend/collab.py. Tests: 17 backend (5 clients simultanes) + 10 frontend. Docs: CHANGELOG, ROADMAP, fiche features/collaboration.md, README FR/EN.

frontend/js/utils.js

@@ -3,6 +3,7 @@ import { api } from './auth.js';
 import { openFile, showWelcome } from './viewer.js';
 import { refreshSidebarForContext, refreshTagsForContext } from './sidebar.js';
 import { createAIToolbar } from './ai.js';
+import { startCollab, stopCollab } from './collab.js';
 
 // ---------------------------------------------------------------------------
 // File extension → Lucide icon mapping
@@ -409,6 +410,13 @@ async function openEditor(vaultName, filePath) {
     bodyEl.appendChild(state.fallbackEditorEl);
   }
 
+  // Real-time collaboration (ROADMAP #62) — bind Yjs to the CodeMirror view.
+  if (state.editorView) {
+    startCollab({ view: state.editorView, vault: vaultName, path: filePath }).catch((err) => {
+      console.warn("Collab start failed:", err);
+    });
+  }
+
   // Set up AI toolbar (recreate each time editor opens)
   var container = document.getElementById('ai-toolbar-container');
   if (container && !container.querySelector('.ai-toolbar') && !container.querySelector('div')) {
@@ -480,6 +488,7 @@ function closeEditor() {
   // Restore brand text
   var brand = modal.querySelector('.editor-brand');
   if (brand) brand.textContent = 'ObsiGate';
+  stopCollab();
   if (state.editorView) {
     state.editorView.destroy();
     state.editorView = null;