test(agentcompat): add integration scenarios

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

integration/agentcompat/internal/scenario/held_nat_proof.go

@@ -0,0 +1,17 @@
+//go:build linux
+
+package scenario
+
+import (
+	"errors"
+	"net/http"
+
+	"github.com/nezhahq/nezha/integration/agentcompat/internal/fixture"
+)
+
+func proveHeldNATRequest(observed fixture.NATEchoRecord, domain, identity string) error {
+	if observed.Method != http.MethodPatch || observed.Path != "/held/"+identity || observed.Host != domain || observed.HeaderValue != identity || string(observed.Body) != "held-body-"+identity || observed.SensitiveHeadersPresent {
+		return errors.New("held NAT request did not match exact protocol proof")
+	}
+	return nil
+}