feat(chat): replace built-in chat with LibreChat SSO integration

Replaces the custom chat page with an external LibreChat instance that
shares Keycloak SSO for seamless auto-login. Removes Tools and Knowledge
Base pages as these are now handled by LibreChat's built-in capabilities.

- Add LibreChat service to docker-compose with Ollama backend config
- Add Keycloak OIDC client (certifai-librechat) with prompt=none for
  silent SSO
- Create librechat.yaml with CERTifAI branding, Ollama endpoint, and
  custom page title/logo
- Change sidebar Chat link to external URL (opens LibreChat in new tab)
- Remove chat page, tools page, knowledge base page and all related
  components (chat_sidebar, chat_bubble, chat_input_bar, etc.)
- Remove tool_card, file_row components and tool/knowledge models
- Remove chat_stream SSE handler (no longer needed)
- Clean up i18n files: remove chat, tools, knowledge sections
- Dashboard article summarization via Ollama remains intact

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

assets/i18n/fr.json

@@ -38,8 +38,6 @@
     "dashboard": "Tableau de bord",
     "providers": "Fournisseurs",
     "chat": "Chat",
-    "tools": "Outils",
-    "knowledge_base": "Base de connaissances",
     "developer": "Developpeur",
     "organization": "Organisation",
     "switch_light": "Passer en mode clair",
@@ -72,28 +70,6 @@
     "trending": "Tendances",
     "recent_searches": "Recherches recentes"
   },
-  "chat": {
-    "new_chat": "Nouvelle conversation",
-    "general": "General",
-    "conversations": "Conversations",
-    "news_chats": "Conversations actualites",
-    "all_chats": "Toutes les conversations",
-    "no_conversations": "Aucune conversation pour le moment",
-    "type_message": "Saisissez un message...",
-    "model_label": "Modele :",
-    "no_models": "Aucun modele disponible",
-    "send_to_start": "Envoyez un message pour demarrer la conversation.",
-    "you": "Vous",
-    "assistant": "Assistant",
-    "thinking": "Reflexion en cours...",
-    "copy_response": "Copier la derniere reponse",
-    "copy_conversation": "Copier la conversation",
-    "edit_last": "Modifier le dernier message",
-    "just_now": "a l'instant",
-    "minutes_ago": "il y a {n} min",
-    "hours_ago": "il y a {n} h",
-    "days_ago": "il y a {n} j"
-  },
   "providers": {
     "title": "Fournisseurs",
     "subtitle": "Configurez vos backends LLM et d'embeddings",
@@ -107,37 +83,6 @@
     "active_config": "Configuration active",
     "embedding": "Embedding"
   },
-  "tools": {
-    "title": "Outils",
-    "subtitle": "Gerez les serveurs MCP et les integrations d'outils",
-    "calculator": "Calculatrice",
-    "calculator_desc": "Calcul mathematique et conversion d'unites",
-    "tavily": "Recherche Tavily",
-    "tavily_desc": "API de recherche web optimisee par IA pour des informations en temps reel",
-    "searxng": "SearXNG",
-    "searxng_desc": "Metamoteur de recherche respectueux de la vie privee",
-    "file_reader": "Lecteur de fichiers",
-    "file_reader_desc": "Lire et analyser des fichiers locaux dans divers formats",
-    "code_executor": "Executeur de code",
-    "code_executor_desc": "Execution de code en bac a sable pour Python et JavaScript",
-    "web_scraper": "Extracteur web",
-    "web_scraper_desc": "Extraire des donnees structurees a partir de pages web",
-    "email_sender": "Envoi d'e-mails",
-    "email_sender_desc": "Envoyer des e-mails via le serveur SMTP configure",
-    "git_ops": "Operations Git",
-    "git_ops_desc": "Interagir avec les depots Git pour le controle de version"
-  },
-  "knowledge": {
-    "title": "Base de connaissances",
-    "subtitle": "Gerez les documents pour la recuperation RAG",
-    "search_placeholder": "Rechercher des fichiers...",
-    "name": "Nom",
-    "type": "Type",
-    "size": "Taille",
-    "chunks": "Segments",
-    "uploaded": "Importe",
-    "actions": "Actions"
-  },
   "developer": {
     "agents_title": "Constructeur d'agents",
     "agents_desc": "Construisez et gerez des agents IA avec LangGraph. Creez des pipelines de raisonnement multi-etapes, des agents utilisant des outils et des flux de travail autonomes.",