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 ./...)