Checkpoint: grpc auth fix, issuer list/detail, v2 protos, architecture docs

Co-authored-by: Junie <junie@jetbrains.com>

internal/engine/ca/ca_test.go

@@ -566,7 +566,7 @@ func TestGetAndListCerts(t *testing.T) {
 		t.Fatalf("list-certs: %v", err)
 	}
 
-	certs, ok := listResp.Data["certs"].([]map[string]interface{})
+	certs, ok := listResp.Data["certs"].([]interface{})
 	if !ok {
 		t.Fatalf("certs type: %T", listResp.Data["certs"])
 	}
@@ -575,7 +575,7 @@ func TestGetAndListCerts(t *testing.T) {
 	}
 
 	// Get a specific cert.
-	serial := certs[0]["serial"].(string) //nolint:errcheck
+	serial := certs[0].(map[string]interface{})["serial"].(string) //nolint:errcheck
 	getResp, err := eng.HandleRequest(ctx, &engine.Request{
 		Operation:  "get-cert",
 		CallerInfo: userCaller(),