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>

librechat/librechat.yaml

@@ -0,0 +1,35 @@
+# CERTifAI LibreChat Configuration
+# Ollama backend for self-hosted LLM inference.
+version: 1.2.1
+
+cache: true
+
+registration:
+  socialLogins:
+    - openid
+
+interface:
+  privacyPolicy:
+    externalUrl: http://localhost:8000/privacy
+  termsOfService:
+    externalUrl: http://localhost:8000/impressum
+  endpointsMenu: true
+  modelSelect: true
+  parameters: true
+
+endpoints:
+  ollama:
+    titleModel: "current_model"
+    # Use the Docker host network alias when running inside compose.
+    # Override OLLAMA_URL in .env for external Ollama instances.
+    url: "http://host.docker.internal:11434"
+    models:
+      fetch: true
+    summarize: true
+    forcePrompt: false
+    dropParams:
+      - stop
+      - user
+      - frequency_penalty
+      - presence_penalty
+    modelDisplayLabel: "CERTifAI Ollama"