Replace concurrent polling of srv.GetListeners() with pre-created
net.Listener injected via srv.SetListeners(). The previous approach
raced with the Start() goroutine writing to s.listeners and calling
net.Listen().
Also remove unused waitForServerRunning call.
Two related fixes that must land together:
1. config.Load() now starts from DefaultConfig() before unmarshaling
YAML. This ensures missing top-level fields (Performance,
Monitoring, Resolver) use their documented defaults instead of
zero values. Most importantly, file_cache is no longer silently
disabled when users omit the performance: section.
2. startSingleMode() now checks Monitoring.Status.Enabled instead of
Path/Allow to decide whether to register the status endpoint.
Without this change, fix#1 would have caused a regression where
the status handler is registered even when monitoring is disabled,
because DefaultConfig() sets Path and Allow defaults.
Also replace remaining log.Printf in status.go and lua/api_timer.go
with zerolog to follow project logging conventions.
Added tests:
- config/load_test.go: verifies defaults are applied, explicit values
override defaults, and monitoring stays disabled by default.
- server/monitoring_registration_test.go: verifies /_status is only
registered when enabled and remains reachable with static handler
on path: /.
