feat(api,ai): #72 OpenAPI 3.1 enrichie + fiabilisation de l'outil AI UI

API (#72):
- backend/openapi_docs.py: 18 tags documentes, assignation auto par prefixe,
  securite bearerAuth/cookieAuth, erreurs 401/403/404/422/500, exemples,
  page /api autonome (liens /docs, /redoc, /openapi.json)
- backend/schemas.py: response_model Pydantic pour ~35 endpoints sans modele
- main.py: FastAPI enrichi + override app.openapi; routes /api et /api/
- ai_routes/bookslm_routes: response_model + doc SSE
- frontend: entree 'API' du menu (i18n FR/EN)
- tests/test_openapi.py (58 tests)

AI UI:
- BooksLM: requetes authentifiees (AuthManager), parsing SSE {token}/error,
  message utilisateur correct (plus le placeholder vide), barre de contexte
- AI Editor: Ctrl/Cmd+J lie une seule fois, libelles i18n, modale de
  reecriture accessible a la place de window.prompt()
- tests/frontend/ai.test.mjs (7 tests) + CI

.gitea/workflows/ci.yml

@@ -38,19 +38,21 @@ jobs:
       - name: Frontend unit tests
         run: node tests/frontend/unit.test.mjs
 
-      - name: Frontend JSDOM tests (PaneManager + Excalidraw + Plugins)
+      - name: Frontend JSDOM tests (PaneManager + Excalidraw + Plugins + AI)
         run: |
           cd tests/frontend
           if [ -d node_modules ]; then
             node pane-manager.test.mjs
             node excalidraw-viewer.test.mjs
             node plugins.test.mjs
+            node ai.test.mjs
           else
             echo "tests/frontend/node_modules missing — installing jsdom"
             npm install --no-audit --no-fund --silent
             node pane-manager.test.mjs
             node excalidraw-viewer.test.mjs
             node plugins.test.mjs
+            node ai.test.mjs
           fi
 
   # ── Tests ─────────────────────────────────────────────────────────