✨ Add file policy drift checks

docs/README-en.md

@@ -231,6 +231,7 @@ match logger.file_runtime_state() {
 - `file_sink(...)` also exposes `rotation_enabled()` and `rotation_config()` for reading whether rotation is active and which parameters are currently in effect.
 - `file_sink(...)` also exposes `state()` for reading a single snapshot that includes path, availability, append policy, auto-flush flag, rotation config, and all current failure counters.
 - `file_sink(...)` also exposes `policy()` and `default_policy()` for reading the current runtime policy and the sink's original default policy separately.
+- `file_sink(...)` also exposes `policy_matches_default()` for explicitly checking whether the current runtime policy has drifted from the original defaults.
 - `file_sink(...)` also exposes `set_policy(...)` for applying append, auto-flush, and rotation as a single bundled runtime policy update.
 - `file_sink(...)` also exposes `reset_failure_counters()` so open/write/flush/rotation failure counters can be cleared after diagnostics or recovery handling.
 - `file_sink(...)` also exposes `reset_policy()` so append, auto-flush, and rotation settings can be restored to the sink's original defaults.
@@ -238,6 +239,7 @@ match logger.file_runtime_state() {
 - `ConfiguredLogger` built through `build_logger(...)` also exposes `file_reopen()`, `file_reopen_with_current_policy()`, `file_reopen_append()`, `file_reopen_truncate()`, `file_flush()`, `file_close()`, `file_append_mode()`, `file_path()`, `file_auto_flush()`, `file_rotation_enabled()`, `file_rotation_config()`, `file_state()`, plus `file_set_append_mode(...)`, `file_set_auto_flush(...)`, `file_set_rotation(...)`, `file_clear_rotation()`, and the corresponding file failure counters, so config-driven file logging keeps a usable control surface.
 - `ConfiguredLogger` also exposes `file_runtime_state()` so queued file loggers can report both the underlying file snapshot and the outer queue backlog/drop state in one read.
 - `ConfiguredLogger` also exposes `file_policy()` and `file_default_policy()` for reading current runtime file policy and initial config policy separately.
+- `ConfiguredLogger` also exposes `file_policy_matches_default()` for explicitly checking whether the current runtime file policy differs from its default config.
 - `ConfiguredLogger` also exposes `file_set_policy(...)` for applying a bundled runtime file policy through the config-built control surface.
 - `ConfiguredLogger` also exposes `file_reset_failure_counters()` for clearing file failure counters through the config-built control surface.
 - `ConfiguredLogger` also exposes `file_reset_policy()` for restoring runtime file policy back to the initial config values.

docs/changes/0.3.0.md

@@ -46,6 +46,7 @@ version 0.3.0
 - feat: add `reset_policy()` / `file_reset_policy()` so runtime append, auto-flush, and rotation settings can be restored to their initial defaults
 - feat: add `policy()` / `default_policy()` and configured-logger forwarding helpers so current runtime file policy and original defaults can be read explicitly
 - feat: add `set_policy()` / `file_set_policy()` so bundled append, auto-flush, and rotation policy can be applied in one runtime operation
+- feat: add `policy_matches_default()` / `file_policy_matches_default()` so runtime file policy drift can be checked explicitly
 - feat: add `SplitSink`, `split_sink(...)`, and `split_by_level(...)` for routing records into different sinks by predicate or level
 - feat: add `Logger::bind(...)` as an ergonomic context-binding alias and `fields(...)` helper for tuple-based field construction