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/function-inventory.md

@@ -84,3 +84,7 @@
 - 本轮扫描到 524 个活跃源码/头文件：18 个 StdAfx 构建支持，142 个已在合同 manifest 中逐文件列出，364 个进入按行为合同归属的静态复核队列；当前未归属行为文件为 0。
 - `EffectLib`、`EterGrnLib`、`MilesLib` 已完成本轮活跃符号和生命周期链静态复核，但仍按实现差异保持 `PARTIAL`；其余 inferred queue 不得因为自动归属而视为已审计。
 - 下次审计必须先运行源码覆盖扫描，再从 `inferred_review_queue` 取下一组，补充对应合同的参考文件、符号、分支矩阵和测试证据；只有完成语义核对后才能转为 `reviewed_static_group`。
+
+### 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`, `costume_system.gd`, `dungeon_ranking_system.gd`, `fishing_cooking_camp_system.gd`, `fishing_mining_system.gd`, `guild_mark_uploader_system.gd`, `guild_war_system.gd`, `horse_combat_system.gd`, `horse_system.gd`, `item_enchant_system.gd`, `item_split_system.gd`, `jewelry_socket_system.gd`, `messenger_system.gd`, `mining_refinery_smelt_system.gd`, `mounted_combat_skill_system.gd`, `npc_shop_system.gd`, `party_management_system.gd`, `pet_companion_system.gd`, `player_trade_exchange_system.gd`, `polymorph_system.gd`, `private_shop_system.gd`, `safebox_storage_keeper_system.gd`, `wardrobe_transmog_system.gd`, `weather_daynight_system.gd`, `world_boss_system.gd`。