swarm-ui: drop an unused export and test the classifier settings logic

The runtime list was exported but only its type was used, so the type is
now written out. The form's pure logic (draft, checks, request body,
change detection) gets tests under node's built-in runner, run by the
existing swarm-ui check.

nix/checks.nix

@@ -369,6 +369,10 @@ in
     buildPhase = ''
       runHook preBuild
       npm run typecheck --workspace=packages/swarm-ui
+      # The package's own tests (`test/`, Node's built-in runner) ride this
+      # derivation: it already has the workspace installed, and a second
+      # `npm ci` for the same tree would only repeat it.
+      npm run test --workspace=packages/swarm-ui
       runHook postBuild
     '';