orion: pin sift 429f6b2 (P3) and drop SearXNG WARNING logs

Sift P3 ships with sources off. SearXNG engine WARNING lines include
q=; LogLevelMax=err keeps those out of the journal. Brave scraper
stays disabled. Do not enable search sources in this commit.

hw/orion/default.nix

@@ -31,6 +31,7 @@
         engines = [
           { name = "bing"; disabled = false; }
           { name = "braveapi"; api_key = "$BRAVE_API_KEY"; disabled = false; inactive = false; }
+          # Scraper logs full q= into the journal on HTTP failures; braveapi covers it.
           { name = "brave"; disabled = true; }
           { name = "duckduckgo"; disabled = true; }
           { name = "startpage"; disabled = true; }
@@ -45,6 +46,10 @@
       };
     };
 
+    # Python WARNING logs from engines include the query string. Restricted
+    # callers must not land q= in a journal fleet logins can read.
+    systemd.services.searx.serviceConfig.LogLevelMax = "err";
+
     # searx-init loads EnvironmentFile at spawn. The file must exist before
     # systemd starts that unit. activationScripts run after users/groups and
     # before units, so the first boot/switch cannot race.