feat: add pastable link for markdown endpoint

src/beaver_gateway/frontends/admin/frontend.py

@@ -629,6 +629,11 @@ def _build_endpoint_catalog(
         )
         markdown_row = {
             "url": f"{markdown_base}/chat",
+            # Bare frontend root for the Obsidian companion plugin — its
+            # settings field asks for the base, then appends ``/chat``,
+            # ``/chat/stream`` itself. Curl + admin /chat tester want the
+            # full ``url`` above; the plugin wants this.
+            "base": markdown_base,
             "vault_path": str(markdown_fe.vault_path),
             "default_agent": markdown_fe.default_agent,
             "log_all_chats": markdown_fe.log_all_chats,