♻️ Harden async logger lifecycle semantics

docs/changes/0.3.0.md

@@ -17,6 +17,7 @@ version 0.3.0
 - feat: add `AsyncLogger`, `async_logger(...)`, `run()`, `wait_idle()`, `close()`, `pending_count()`, and `dropped_count()` on top of `moonbitlang/async`
 - feat: add async logger composition helpers `with_context_fields(...)`, `with_filter(...)`, `with_patch(...)`, `with_target(...)`, `child(...)`, and `with_timestamp(...)`
 - feat: add `AsyncLoggerBuildConfig`, `parse_async_logger_build_config_text(...)`, and `build_async_logger(...)` for config-driven async logger assembly
+- feat: add async lifecycle helpers `shutdown()`, `is_closed()`, `is_running()`, `has_failed()`, and `last_error()` for safer worker teardown and observability
 - feat: expose `Record::new(...)` for adapter and integration layers
 - fix: repair native file backend FFI declarations so native target checks succeed again
 - feat: support config keys `min_level`, `target`, `timestamp`, `sink.kind`, `sink.path`, `sink.append`, `sink.auto_flush`, `sink.text_formatter`, and `queue`