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/movement.keyboard-motion.md

@@ -338,3 +338,7 @@ server_speed_scale = 0.0 if moving_speed > 1100 else float(moving_speed) / 100.0
 - `OnWaiting`：参考只在 `CInstanceBase::Transform()` 的 `IsWalking() || IsUsingMovingSkill()` 分支内、本帧位移 ≤1.0 时调用（`InstanceBase.cpp:1922-1930`），100ms 节流，位移基准为 `m_kPPosPrevWaiting`（由 `OnSyncing`/`OnWaiting` 更新）。当前端原有的 `_tick_on_waiting()` 在站立期间周期补发 `FUNC_WAIT`，参考没有该机制，已删除（含 `SEND_WAITING_*` 与 `_last_waiting_sent_t`）。走/跑中本帧无位移的 OnWaiting 路径尚未移植（DIVERGENT）。
 - `CInstanceBase::SHORSE::SetMoveSpeed` 只同步坐骑模型动画速率，不是另一套移动速度公式，归 `world.mount_pet_polymorph`。
 - 测试：`netplay_test.gd` 新增“站立被推开不发包”断言；netplay/keyboard_motion_timeline/movement_parity/player_move/test_wasd_steering_parity/test_no_auto_move_regression/motion_event_warp/playable_combat 均 PASS。
+
+### 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_alignment_parity.gd`。