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.affect-status.md

@@ -93,3 +93,7 @@
 - 为每个 affect bit 建立 40250 资源、附着骨骼、开关、清理和石头烟雾矩阵。
 - 增加 `GC_AFFECT_ADD → duration → GC_AFFECT_REMOVE`、重复/乱序/重连/换图的 native→HUD 端到端测试。
 - 增加远端 Actor 的 stunned/knockdown/skill-cancel 状态机测试，并修复 `hit_view_test.gd` 的前向 damage 资源选择后再提升合同状态。
+
+### 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：`combat_status_effect_system.gd`, `test_combat_status_effect_parity.gd`, `test_mob_combat_reaction_parity.gd`。