orion: enable sift searxng, brave_llm, tavily

Bake-off sources. SearXNG journal is already LogLevelMax=err.
Keys stay in /var/lib/sift/secret.env, not the store.

hw/orion/default.nix

@@ -105,6 +105,26 @@
           workspaces = [ "hermes-fleet" "guardian-star" ];
           permit_restricted = [ "straylight-gs" ];
         };
+        search = {
+          k = 8;
+          timeout = "8s";
+          rerank = true;
+          digest = false;
+          cache_ttl = "1h";
+          searxng = {
+            enabled = true;
+            url = "http://127.0.0.1:8888";
+          };
+          brave_llm = {
+            enabled = true;
+            url = "https://api.search.brave.com/res/v1/llm/context";
+          };
+          tavily = {
+            enabled = true;
+            url = "https://api.tavily.com/search";
+            daily_credit_cap = 500;
+          };
+        };
       };
     };