docs: condense #7830 changelog entry

Author: Ralph Küpper

changelog.d/7830-file-size-gate.md

@@ -1,23 +1,3 @@
-### Fixed
-
-- **`lint` is green again: two files had crossed the 2000-line cap on `main`.**
-  `crates/perry-hir/src/lower/pre_scan.rs` went 1985 → 2011 in #7828 and
-  `crates/perry-runtime/src/gc/layout.rs` went 1982 → 2010 (#7809) → 2023
-  (#7812), so `scripts/check_file_size.sh` — and with it the whole `lint` job —
-  failed on every commit after that batch.
-
-  Both are pure code moves with no logic change:
-
-  - `pre_scan_weakref_locals` and its doc comment move to
-    `lower/pre_scan/weakref_locals.rs`, leaving 1653 lines behind. It is the
-    natural unit: one of the file's three top-level pre-scans, owning its own
-    five local-name sets, and the one #7828 grew.
-  - `LayoutSlotMask` — the enum and its entire `impl` — moves to
-    `gc/layout/slot_mask.rs`, leaving 1807 lines behind. Its visibility widens
-    from `pub(super)` to `pub(in crate::gc)` only because the type now sits one
-    module deeper while `layout_tables.rs` and `hot_tls.rs` still name it; the
-    set of modules that can reach it is unchanged.
-
-  The cap is cheap to check and expensive to notice late — `bash
-  scripts/check_file_size.sh` before pushing is the whole remedy, and it is
-  already written down in CLAUDE.md's "CI gates that surprise people".
+**The 2,000-line file-size lint gate passes again.** The GC layout slot-mask
+implementation and weak-reference local pre-scan now live in dedicated modules,
+without behavior changes.