Playtest #4 fixes: tile picking, knocked-down state, element gauges, draft timer, live stats, shop items, drones, 赫默, 炎佑, UI flash

- #1 picking by the tile under the pointer (prep, battle, pen, equipment drops); the dragged model stays
  under the pointer (mouse and touch); pixel probe removed; phone ghost-click on the underframe fixed
- #2 two-tap confirm on 机变 cards (like the shop)
- #3 a 同盟 room with one human is untimed like 独立模拟 (no countdown outside battles)
- #4 strategy draft: one synced countdown, 30 s per human turn, timeout takes the highlighted band
- #5 special 维式重锤 (4) and 突变细胞 no longer sold; item card shows where they come from
- #6 operator skill-mode sounds no longer play on normal attacks (纯烬艾雅法拉 and 55 others)
- #7 detail card shows live battle stats and the prep-time battle-start stats (g.unitStats)
- #8 official element gauges on units; burst cooldown (阻回) per PRTS
- #9 knocked-down operators stay on their tile with a redeploy countdown ring
- #10 drone behaviour per PRTS (暴鸰, 先兆者 shells, 黑云, 萨科塔之眼)
- #11 赫默's drone only from her skill; placeable summons limited to talent tokens
- #12 炎佑 stays where it is with no enemies; 祛恶之焰 as a continuous channel
- #13 the occasional giant bond icon (loading texture scaled ×46) fixed
- docs (DESIGN §18), recordings, data and tests updated (2467 unit tests, all browser suites green)

server/sim/simdata.js

@@ -44,6 +44,16 @@ export function flattenBlackboard(bb) {
 
 const num = (v, d = 0) => (typeof v === 'number' && Number.isFinite(v) ? v : (typeof v === 'string' && v.trim() !== '' && Number.isFinite(+v) ? +v : d));
 
+/**
+ * Is an items.json record a shop item — what the 调度中心 item slot, the 道具补给 / 机密商店 cards and the "random
+ * item" pools (pool_equip_normal …) draw from: a normal EQUIP item with a tier, neither hidden by the official shop
+ * table (`hideInShop`: the Arts) nor one of the effect-only items build-data marks `shopExcluded` (the special
+ * 维式重锤 of 维多利亚 / 洛洛, 突变细胞 — tools/build-data.mjs SHOP_EXCLUDED_ITEMS).
+ */
+export function isShopItem(it) {
+  return !!it && typeof it === 'object' && !it.isGolden && !it.hideInShop && !it.shopExcluded && it.itemType === 'EQUIP' && Number.isInteger(it.tier);
+}
+
 function toArrayOfPairs(grid) {
   if (!Array.isArray(grid)) return null;
   const out = [];