test(contracts): add /v1/agents HTTP contract test

tests/contracts/http_api/agents_test.go

@@ -0,0 +1,25 @@
+//go:build integration
+
+package http_api
+
+import "testing"
+
+// CONTRACT: /v1/agents response MUST include agents array.
+func TestContract_HTTP_AgentsList(t *testing.T) {
+	baseURL, token := getTestServer(t)
+	client := newHTTPClient(baseURL, token)
+
+	resp := client.get(t, "/v1/agents")
+
+	assertField(t, resp, "agents", "array")
+
+	agents, ok := resp["agents"].([]any)
+	if !ok || len(agents) == 0 {
+		t.Log("No agents - skipping field checks")
+		return
+	}
+
+	agent := agents[0].(map[string]any)
+	assertField(t, agent, "id", "string")
+	assertField(t, agent, "agent_key", "string")
+}