Living Signals MCP server. POST JSON-RPC 2.0 here. Tools: list_countries, get_rubric, list_annotation_layers, search_signals, describe_signal, list_topics, list_claims, search_claims, get_claim, get_top_places, list_my_dossiers, get_dossier, create_dossier, save_to_dossier, attach_draft_to_dossier