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/item.refine-socket-costume.md

@@ -120,3 +120,7 @@
 - `EntityStore` 的正 HP 点数更新会清除 `dead`，`M2Client` 会重置 `dead_seen`，保证复活后下一次死亡可以再次发出 `entity_dead`。
 
 本合同继续为 `PARTIAL`：本轮只修复了可直接验证的协议边界和死亡状态边沿，没有把本地属性/镶嵌/时装旁路误标为 40250 等价实现。
+
+### 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：`costume_attr_transfer_system.gd`, `costume_system.gd`, `item_enchant_system.gd`, `jewelry_socket_system.gd`, `refine_effect_system.gd`, `test_costume_attr_transfer_parity.gd`, `test_costume_system_parity.gd`, `test_item_enchant_manager_parity.gd`, `test_jewelry_socket_parity.gd`, `test_refine_effect_parity.gd`, `test_wardrobe_transmog_parity.gd`, `wardrobe_transmog_system.gd`。