refactor(agent): dedupe harness and command workflows

src/cli/requirements-test-fixtures.ts

@@ -0,0 +1,18 @@
+export function createEmptyRequirements() {
+  return {
+    bins: [],
+    anyBins: [],
+    env: [],
+    config: [],
+    os: [],
+  };
+}
+
+export function createEmptyInstallChecks() {
+  return {
+    requirements: createEmptyRequirements(),
+    missing: createEmptyRequirements(),
+    configChecks: [],
+    install: [],
+  };
+}