feedback1 cell: a 突变细胞 transformation gains the new operator into the 整备区 and frees the carrier's tile (pointed out in PR #2)

Official gameplay footage (bilibili BV1vzyVBuEN9 at about 8:24, BV1Qkw1zMEoR at about 7:25) shows the
next prep with the carrier's tile empty, one more deployment left, and the returned equipment plus the
new tier+1 operator on the bench, deployed by hand afterwards. That is the PRTS 备注 read as written
("生效时，原干员销毁，获得一名高一阶的随机初始干员"): a destroy followed by a gain. The closed PR #2 made
the same claim from a playtest.

- PlayerState.transformChess: the carrier is destroyed wherever it stands (board tile freed, summons
  removed, copies back to the pool); its equipment, the cell included, returns to the hand first
  (overflow temp, auto-merge); then the new operator is gained through acquireChess like any gained
  operator (hand, overflow temp, the no-room rule of every gain; no summon card until it is deployed).
  The returnItems option is gone (the cell's built-in was its only caller).
- A merge the gain completes merges like any gained copy: the elite takes a consumed deployed copy's
  tile, else the hand. _mergeChess loses fromKey / fromDir, so the destroyed carrier's tile never
  counts (PR #2 had kept that path; not adopted); audit.js drops its exception for it.
- builtinMeta, ctx.transform, items/meta.js and bot.js comments follow. Bots and AI 托管 deploy the
  gained operator in their normal lineup step (no bot change needed; a real co-op round pins it).
- ITEM_RULES note and implFormula for the item card; data/items.json rebuilt with build-data --offline.
- Tests: facing, merge, playtest6-elite-to-board and items no longer pin the kept tile; feedback1-meta
  covers a deployed and a bench carrier, hand full -> temp, hand and temp full, a merge with and
  without a deployed copy (never the carrier's tile), 商业包装方案's count on the returned item, and bots /
  AI 托管 redeploying; feedback1-cell checks the new note.

server/match/builtinMeta.js

@@ -17,9 +17,10 @@
 //   use_equip_recruit_new_char_and_give_char_to_player_most_bond {refresh_cnt} 信标 destroy target, offer N same-tier
 //                                                                                chess, gift the original next prep
 //   sell_char_count_gain_equip_owner_bond {count}         商业包装方案           every `count` sells → same-bond chess
-//   char_chess_transformation_equip                       突变细胞               after battle: holder → random NORMAL tier+1
-//                                                                                (max 6); its equipment, the cell included,
-//                                                                                returns to the hand (not consumed)
+//   char_chess_transformation_equip                       突变细胞               after battle: holder destroyed, its equipment
+//                                                                                (the cell included — not consumed) back to
+//                                                                                the hand, then a random NORMAL tier+1 (max 6)
+//                                                                                operator gained into the hand
 //   trap_copy_front_char                                  画卷 (Art)            copy the chess on the tile / in front
 //   trap_create_self_choice {choice_event}                教鞭 / 神秘顾客 (Art)  add a random bounty to your next battle
 // [ASSUMED simplification, documented in docs/META.md: 教鞭/神秘顾客 pick the bounty for the player instead of opening
@@ -177,12 +178,15 @@ const ITEM_HANDLERS = {
       }
     },
   },
-  // 突变细胞 "战斗结束后，装备者替换为高一阶的随机干员": the carrier is replaced by a random NORMAL operator one tier higher
-  // (at most 6; an elite carrier too — PRTS 卫戍协议：盟约 下半/PRTS盟约记录 备注 "生效时，原干员销毁，获得一名高一阶的随机
-  // 初始干员（最高六阶）"); the destroyed operator's equipment, the cell included, returns to the hand (PRTS 卫戍协议/帮助
-  // "佩戴的装备无法手动卸除，在失去该干员（干员出售、销毁、合并等）或装备合并为进阶品质时自动卸除"; the official text never
-  // says 销毁 for the cell — unlike every consumable item —, and players re-inject it every round: "之后就是一直打针，扎到
-  // 核心卡…就换人扎", bilibili cv47000418; player feedback after 0.1.0). The new operator keeps the tile when legal.
+  // 突变细胞 "战斗结束后，装备者替换为高一阶的随机干员": PRTS 卫戍协议：盟约 下半/PRTS盟约记录 备注 "生效时，原干员销毁，获得
+  // 一名高一阶的随机初始干员（最高六阶）" — the carrier (deployed or on the bench) is destroyed and a random NORMAL operator
+  // one tier higher (at most 6; an elite carrier too) is gained like any gained operator: into the 整备区 (overflow temp),
+  // never onto the carrier's tile — official footage (bilibili BV1vzyVBuEN9 ≈ 8:24, BV1Qkw1zMEoR ≈ 7:25): at the next
+  // prep the tile is empty, one more deployment is left and the new operator waits on the bench (pointed out in PR #2).
+  // The destroyed operator's equipment, the cell included, returns to the hand first (PRTS 卫戍协议/帮助 "佩戴的装备无法
+  // 手动卸除，在失去该干员（干员出售、销毁、合并等）或装备合并为进阶品质时自动卸除"; the official text never says 销毁 for the
+  // cell — unlike every consumable item —, and players re-inject it every round: "之后就是一直打针，扎到核心卡…就换人扎",
+  // bilibili cv47000418; player feedback after 0.1.0). PlayerState.transformChess.
   char_chess_transformation_equip: {
     onBattleResult(ctx) {
       const { piece, holder } = ctx.source;
@@ -190,7 +194,7 @@ const ITEM_HANDLERS = {
       const tier = Math.min(6, ctx.gd.tierOf(holder.id) + 1);
       const id = ctx.rollChess({ tier });
       if (!id) return;
-      ctx.transform(holder.uid, ctx.gd.baseIdOf(id), { returnItems: true });
+      ctx.transform(holder.uid, ctx.gd.baseIdOf(id));
     },
   },
   trap_copy_front_char: {