## Summary
- Replace guard-clause-based `should_skip_snmp/service/ping_check?` with a single `should_skip_check?` function using runtime `in` operator checks
- Guard clauses with module attributes (`@service_check_types`) were not working in Dokku buildpack deployments despite code being correct locally
- Also update `CheckWorker` (dead code safety net) to check `device_has_effective_agent?`
- Use `Logger.info` for skip messages so they appear in staging logs
## Context
PR #77 introduced `device_has_effective_agent?/1` and updated all workers, but the guard-clause-based skip functions in `CheckExecutorWorker` weren't matching at runtime on staging despite passing all tests locally. The DNS check kept producing NXDOMAIN errors from Erlang's `:inet_res` resolver.
Root cause: The `when check_type in @service_check_types` guard clause compiled against module attributes appears to have stale evaluation in the Dokku Heroku buildpack release. Moving the check to a runtime function body fixes the issue.
## Test plan
- [x] All 230 worker tests pass
- [x] All 99 agents tests pass
- [x] Verified on staging: "Skipping check eceb3d51... (dns)" appears in info logs
- [x] No new NXDOMAIN results created after deploy
Reviewed-on: graham/towerops-web#78
Graham McIntire
d6f7dc570a