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/skill.player-ui-cooldown.md

@@ -148,3 +148,7 @@
 - `player_skill_test`、`skill_test`、`guild_war_skill_test` 均通过，覆盖非公会战拒绝、公会战独立包和 UI 公会技能页。
 
 仍保持 `PARTIAL`：真实 `GUILD_WAR_ON_WAR` 回包、服务端拒绝/冷却回滚、跨生命周期乱序和完整动作/damage 证据尚未闭合。
+
+### 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：`test_status_skill_reset_parity.gd`。