Fix all golangci-lint warnings

- errorlint: use errors.Is for db.ErrNotFound comparisons
  in accountservice.go, credentialservice.go, tokenservice.go
- gofmt/goimports: move mciasv1 alias into internal import group
  in auth.go, credentialservice.go, grpcserver.go, grpcserver_test.go
- gosec G115: add nolint annotation on int32 port conversions
  in mciasgrpcctl/main.go and credentialservice.go (port validated
  as [1,65535] on input; overflow not reachable)
- govet fieldalignment: reorder Server, grpcRateLimiter,
  grpcRateLimitEntry, testEnv structs to reduce GC bitmap size
  (96 -> 80 pointer bytes each)
- ineffassign: remove intermediate grpcSrv = GRPCServer() call
  in cmd/mciassrv/main.go (immediately overwritten by TLS build)
- staticcheck SA9003: replace empty if-body with _ = Serve(lis)
  in grpcserver_test.go
0 golangci-lint issues; 137 tests pass (go test -race ./...)

internal/grpcserver/auth.go

@@ -12,11 +12,11 @@ import (
 	"google.golang.org/grpc/status"
 	"google.golang.org/protobuf/types/known/timestamppb"
 
+	mciasv1 "git.wntrmute.dev/kyle/mcias/gen/mcias/v1"
 	"git.wntrmute.dev/kyle/mcias/internal/auth"
 	"git.wntrmute.dev/kyle/mcias/internal/crypto"
 	"git.wntrmute.dev/kyle/mcias/internal/model"
 	"git.wntrmute.dev/kyle/mcias/internal/token"
-	mciasv1 "git.wntrmute.dev/kyle/mcias/gen/mcias/v1"
 )
 
 type authServiceServer struct {
@@ -97,8 +97,8 @@ func (a *authServiceServer) Login(ctx context.Context, req *mciasv1.LoginRequest
 		return nil, status.Error(codes.Internal, "internal error")
 	}
 
-	a.s.db.WriteAuditEvent(model.EventLoginOK, &acct.ID, nil, ip, "")             //nolint:errcheck
-	a.s.db.WriteAuditEvent(model.EventTokenIssued, &acct.ID, nil, ip,             //nolint:errcheck
+	a.s.db.WriteAuditEvent(model.EventLoginOK, &acct.ID, nil, ip, "") //nolint:errcheck
+	a.s.db.WriteAuditEvent(model.EventTokenIssued, &acct.ID, nil, ip, //nolint:errcheck
 		fmt.Sprintf(`{"jti":%q}`, claims.JTI))
 
 	return &mciasv1.LoginResponse{