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/world.fishing-mining.md

@@ -86,3 +86,7 @@
 本轮仍为 `PARTIAL`；完成钓鱼/采矿方向的合同审计并登记，未修改实现。
 
 `PARTIAL`。当前端已经具备 40250 钓鱼/采矿协议骨架、角色动作入口、水属性扫描和水面构造；但持竿/持镐 live 门控、角色状态条件、采矿 count 动作队列和真实资源副作用证据不足，且钓鱼收益、烹饪、营火、熔炼、宝石与库存脚本承担了 40250 客户端没有承担的本地 authority。本轮完成审计并记录，未修改实现。
+
+### 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：`fishing_cooking_camp_system.gd`, `fishing_mining_system.gd`, `fishing_rod_reel_system.gd`, `mining_refinery_smelt_system.gd`, `test_fishing_cooking_camp_parity.gd`, `test_fishing_mining_parity.gd`, `test_fishing_rod_reel_parity.gd`, `test_mining_refinery_smelt_parity.gd`。