Add MCP auth status to kb_status and update server instructions

- kb_status now returns authenticated: true/false so clients can verify auth
- Server instructions mention Bearer token auth requirement
- Add .env, .venv/, test_mcp_client.py to .gitignore

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -4,3 +4,6 @@ __pycache__/
 engine/data/
 
 TMP/
+.env
+.venv/
+test_mcp_client.py