cargo fmt regroups, plus three Phase-B clippy fixes:
- F-P-004: #[allow(clippy::type_complexity)] on the invoke_ast_cache Mutex.
- F-P-008: hoist `futures::stream::{self, TryStreamExt}` to the top-of-
file imports to satisfy clippy::items_after_statements.
- F-P-005: rename `_legacy_offset` to `legacy_offset` + #[allow(dead_code)]
to satisfy clippy's "field is pub but `_`-prefixed" check.
No behavior change.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
dc40bc7926