卫戍协议：盟约 web remake — initial import

Online co-op browser remake of Arknights' Stronghold Protocol: Alliance
(client-simulated combat, official waves/bonds/items/strategies, 3D board,
facing wheel, operator loadout, official emotes, deployment scripts).

server/sim/content/items.js

@@ -0,0 +1,6 @@
+// server/sim/content/items.js — equipment & Arts content (research 04, docs/DATA.md §5).
+// Battle side: install(battle) is called once per Battle by content/index.js (inside try/catch).
+// Prep side: registerMeta(registry) is called once at server boot by match/effectsMeta.js.
+// lendItemEffects(battle, fromUnit, toUnit, { maxTier, duration }) is used by 萨尔贡 × 娜仁图亚 (bands).
+export { install, lendItemEffects } from './items/battle.js';
+export { registerMeta } from './items/meta.js';