## Summary
- **DNS checks**: `parse_server` returned a flat 5-tuple `{a,b,c,d,53}` instead of `{{a,b,c,d}, 53}` — the format `:inet_res` requires for nameservers. All DNS checks using a custom server failed with argument error.
- **Ping checks**: `System.cmd` `:timeout` option not supported on Elixir 1.19.4 (staging). Replaced with `Task.async`/`Task.yield` wrapper for cross-version compatibility.
- **Checks table UI**: Removed unnecessary flex div wrapper on status badge column that caused vertical misalignment with other table cells.
## Test plan
- [x] DNS executor tests pass (custom server resolution now succeeds)
- [x] Ping executor tests pass (no more ArgumentError)
- [x] Full test suite passes (8593 tests, 0 new failures)
Reviewed-on: graham/towerops-web#72
Graham McIntire
f05cc32ef6