The bond bar can be folded, so the board stays tappable on phones (#149)

The fold state stays for the match; Space does not ready or pause at the same time. Closes #142. Contributed by @CELLOPOI.

docs/DESIGN.md

@@ -492,6 +492,8 @@ Look & feel: research 06 §11–§12 (near-black green-grey panels, mint `#4ed8a
 
 Screens: **Title** (season art backdrop, 开始 → nickname), **Lobby** (独立模拟 / 同盟模拟 → create or join; recent rooms), **Room** (4 seats, invite code + copy link, difficulty picker (host), add/remove AI, ready, start), **Briefing** (INFO_CHECK: stage, factions, disabled bonds, banned chess, boss silhouette, ready x/4), **Band draft** (grid of 40 bands with icon/name/LP/effect; turn order list; skip; 查看禁用盟约与干员 under the order list opens the briefing's bond rows, legend and banned operators again in a read-only dialog — one component, `ui/matchInfo.js`, §21.28), **Game** (Pixi field + DOM HUD: top bar with round/phase capsule/LP (live during the own battle, §17.5)/timer/ready; bond strip + popups; left team panel with LP/status/emote bubbles, click to watch; bottom shop bar (level card, 3–5 chess cards, item card, funds, refresh, freeze, collapse); detail panel on click/hover (header with bonds, then 特质 — the operator's own effect — right under it, 特性, stats (live: the battle's own numbers / the start-of-battle ones in prep, §18.5), skill, module, equipped items, talents: §17.5); enemy preview drawer (next round enemies with counts, factions; its 本局信息 tab lists the briefing's disabled bonds and banned operators, §21.28); 机变 overlay (the official card: framed icon + name, the effect text — data `descRaw` — under it, the taker's round avatar at the top-right; two taps, §18.2, §20.7); merge reward overlay (the promotion reward, or a special offer — 凯瑟琳's 定向投放 … — as item / chess cards under its source's label, with the count of offers queued behind it, §21.2); phase banners; ticker (by broadcast priority, highest first; a leader-damage line plays only in its round and a player's newer one replaces the older, §21.10); toasts; emote wheel; settings (volume, quality, show damage numbers)), **Result** (victory/defeat, rounds, per-player lineup, stats, titles, back to room).
 
+盟约栏支持「收起／展开盟约」（GitHub #142）：收起时隐藏完整列表并关闭由列表打开的浮层，让原图标区域的指针事件到达棋盘，只保留至少 44×44 CSS px 的恢复按钮。折叠状态在本局阶段变化、观看队友时保留；展开后仍按当前观看对象显示最新盟约。按钮支持 Enter / Space，聚焦按钮时 Space 不触发准备或暂停。
+
 A bond the mode never activates (标准: official `inactiveBondIdList`) reads 本局禁用 on shop / reward cards (struck through), detail chips and the popup — no 在场 count, no 当前效果 (§21.7); a strategy built around one carries a 本局禁用 tag and note in the strategy draft and stays selectable (bands.json `bondIds`, §21.26).
 
 Interactions (research 09 §1.2 / §5, which supersede the first draft): shop card, upgrade and 机变 card are two-tap (select → confirm, §18.2) — a tap anywhere on the card, its confirm strip included, is the card's tap (shop cards have no ⓘ corner; the armed bar sits above the detail card; a shop card that cannot be bought right now opens its detail on tap, §20.7); a press / drop goes by the tile under the pointer (§18.1); drag bench↔board — a legal board drop (also onto the piece's own tile) opens the 4-direction deploy wheel (swipe UP/RIGHT/DOWN/LEFT with the rotated range striped orange; release in the centre, ✕ 点击取消 or Esc cancels); tap a unit's tile ⇒ underframe with **出售 +N** (and **撤退** on the board; items/Arts in the hand / temp: **销毁** — equipped items are locked, §6.2) plus its rotated range; no drag-to-sell; drag an item onto a unit's tile ⇒ equip that unit (both slots used ⇒ the replace dialog `ui/equipReplace.js` shows the incoming and the two equipped items; the player picks the one to replace — it is destroyed — `g.equip replaceUid`; cancel changes nothing); Arts are dropped on a tile and get the direction step; right-click or long-press ⇒ detail (or a tap on a shop card while the bar is locked); `R` refresh, `F` freeze, `D` level-up, `Space` ready (in a solo battle: pause / resume, §14 Solo pause). All actions optimistic-free: UI waits for server state (latency is small).