feedback1 WA: return the Mutation Cell before summon cards; bots keep it

Review follow-ups for reports #1 and #4.

- transformChess: the returned equipment is stowed before the new operator's
  summon stack is granted (as in _mergeChess); when the transformation
  completes a merge, the carrier's equipment goes through _mergeChess, which
  also returns it before the elite's summons. A summon card no longer pushes
  the returned 突变细胞 into temp, where it would be lost at the deadline.
- bot: a 突变细胞 left in temp with a full hand gets a hand slot (sell the
  weakest single hand chess, else destroy the cheapest other hand item, else
  sell any hand chess) instead of being destroyed.
- 拉普兰德's per-piece counter key is module-prefixed; the re-bought copy
  case is marked [ASSUMED] in the code and docs/META.md.
- .dhint--rule gets a style; sources quote PRTS 卫戍协议/帮助 exactly
  ("在失去该干员（干员出售、销毁、合并等）…时自动卸除").

public/css/screens/game-panels.css

@@ -201,6 +201,8 @@
 .dhint .icon { width: .16rem; height: .16rem; margin-top: .03rem; flex: none; }
 /* a merge-completing shop / reward card's 可晋升 destination (the tag's colour; touch shows no title — QA 6b) */
 .dhint--merge { color: var(--gold); }
+/* a rule the official item text leaves out (items.json `note`: 突变细胞 returns to the hand after each use) */
+.dhint--rule { color: var(--text-md); }
 .dactions { display: flex; justify-content: flex-end; gap: .1rem; padding-top: .06rem; border-top: 1px solid var(--line); }
 .dsell { margin-left: .06rem; color: #1d1400; }
 .dfactions { display: flex; flex-wrap: wrap; gap: .06rem; }