Split CI pipeline into separate stages: lint, test, analyze, publish

[steindvart]

Problem

Right now the GitHub Actions pipeline runs all checks in a single job. This means every check runs sequentially in one stage and we lose clarity and flexibility. It also makes it harder to:

• Run fast checks in parallel
• Fail early on linting or analysis problems
• Reuse or cache steps like Go setup or module caching across related jobs
• Make the publish step depend clearly on successful tests only

Proposal

1. Make container-based jobs to avoid "Install Go" step.
2. Split the pipeline into these jobs:
   • lint - run linters (golangci-lint)
   • analyze - run static code analyzers (for example gocyclo, staticcheck)
   • test - run unit tests and produce coverage
   • publish - publish results (codecov, etc.)

Design notes:

• test should depend on lint and analyze.
• publish should run only after test succeeds.

Arguments

• Faster feedback: lint and analysis can run in parallel and fail early.
• Clearer pipeline: each job has a single responsibility and easier to read.
• Easier to maintain: adding or removing checks is simpler.
• Safer publishing: publishing steps run only after tests pass.