chore: delete 106 unreachable *_system.gd and their parity tests

These files were loaded only by their own test_*_parity.gd and never by
the runtime (transitively checked, incl. client_phase_integration_system).
Removes 76 manifest implementation/evidence references across 18
contracts; contract docs get a note that conclusions based on them are
void. Live systems kept: chest, consumable, item_attr, metin_socket,
whisper_chat.

Full headless suite: no new failures (7 failing + 5 headless-hanging
render tests are identical before the deletion).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

audit/contracts/combat.attack-combo-damage.md

@@ -237,3 +237,7 @@ native `CActorInstance` 的同一骨骼 composite matrix、旋转和绑定坐标
 进程退出码为 0；此前记录的 race 0 / 03150 左手贴合断言失败不再是当前待办项，已从
 manifest 的 `remaining` 移除。该校正只更新证据状态，不改变 WeaponTrace native
 骨骼 composite matrix、远端/怪物覆盖和服务端攻击闭环仍未证明的结论。
+
+### 2026-09-22 死代码删除
+
+以下文件只被自身测试引用、运行时从不加载，已删除；本文中以它们为实现或证据的结论作废，相关行为需按 40250 源码单元重新移植：`socket_glow_fx_system.gd`, `test_combat_status_effect_parity.gd`。