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/social.chat-text-tail.md

@@ -127,3 +127,7 @@
 ## Status
 
 `PARTIAL`。当前端已有聊天协议骨架、公共输入、私聊基础发送、聊天气泡和名字尾标的可测试镜像，但并非与 40250 统一实现：live 私聊已接入独立会话，但窗口历史/任务栏通知/服务端 ignore 命令仍未闭环；公共颜色/notice 分支不一致、入站表情/过滤/跨帝国文本缺失，且尾标渲染仍使用 Godot billboard 与宽度估算。本轮已修正 whisper mode 映射、空错误文案、截断 whisper 拒绝逻辑并接通 live conversation/ignore 判断，其他差异继续保持 PARTIAL。
+
+### 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_chat_hyperlink_dice_parity.gd`。