- Fixes a bug where the log level set in the config file was
ignored: `Logger` and `StderrLogger` captured the level in a
`self.level` field at construction time and checked it in
`Log::enabled`. After config was loaded, the global
`log::set_max_level` was updated but `self.level` was not,
so verbose messages were dropped by the per-instance filter
even when the global filter allowed them.
- Make `log::set_max_level` the single source of truth: remove
the `level` field and have `Log::enabled` defer to
`log::max_level()` so the two filters can no longer drift.
- Update call sites to construct loggers without a level.
- Disable the structured logger's internal filter (set to "trace") so
that it also falls back to `log::set_max_level`.
6b460c4429