feedback5 WY: 拟态物质 with 2 copies owned and none left in the pool gives nothing instead of a random same-bond operator (GitHub #207)

The item text 「若已拥有至少2名该初始干员，则再获得1名该初始干员；否则随机获得1名同盟约初始干员」: the 否则 is the
case of fewer than 2 owned. builtinMeta's use_equip_reward_char_chess returned only when grantChess(base) gave a piece,
so an elite 溯光星源 plus 2 normal copies (all 5 Ⅵ阶 copies) fell through to the same-bond roll (白面鸮 in the report's
seed). Now with 2 owned it asks for the 3rd and stops; the item is still consumed. The bots' carrier choice
(itemTarget) skips 2 copies whose pool is out.

Tests: test/content/items.test.js (the report with the normal and golden item; 2 copies with the pool drained; 2 copies
with copies left still merge), test/match/bot-smarter.test.js (no carrier on a pair whose pool is out); both fail
without the fix. Docs: META built-ins and bot items, research 04 / 06, DESIGN §25.13.1.
Golden unchanged.

docs/research/06-multiplayer-ux.md

@@ -358,7 +358,7 @@ Visual [SHOT]: the banner is a dark strip with orange chevrons and orange-skull
 - A **normal** unit uses 1 copy and an **elite** uses 3.
 - **Counted:** units on every player's battlefield, bench and temp bench, from any source (buy, reward, strategy effect, 拟态/copy effects).
 - **Not counted:** cards currently displayed in any shop.
-- When owned copies ≥ the cap, a refresh can't roll that name. Some effects fail when the cap is hit (杜遥夜's search; possibly 拟态物质 or 煌's sell effect).
+- When owned copies ≥ the cap, a refresh can't roll that name. Some effects fail when the cap is hit (杜遥夜's search; possibly 拟态物质 or 煌's sell effect). [0.2.0: the remake's 拟态物质 gives nothing when 2 copies are owned and none is left — GitHub #207; its 否则 same-bond operator is only for fewer than 2 owned.]
 - Selling (1 fund per bench unit) returns copies. A player's **defeat or quit returns all their copies immediately**.
 - The server must own the pool (authoritative) and update it in real time for everyone.