feat(orbit): per-guest suggestion mute + global pending-cap setting

Two anti-spam knobs the host can dial during a live session:

1. Per-guest suggestion mute — Mic / MicOff toggle next to the
   kick/ban buttons in the participants popover. Symmetric (re-enable
   later). State lives in OrbitState.suggestionBlocked: string[]; the
   guest reads it and disables its own Suggest controls so the user
   sees a clear "muted" state instead of silent failures. Host-side
   sweep also drops their outbox entries as a safety net.

2. Max pending approvals cap — number input in the session-settings
   popover, default 0 (= unlimited so existing sessions are unaffected).
   When set, the host sweep stops folding new outbox entries into the
   approval list once the cap is reached. The OrbitQueueHead surfaces
   "X / Y pending" so guests can see when they're getting close.

State changes are additive on the wire — both fields are optional, with
parseOrbitState defaulting them, so older clients keep working.

evaluateOrbitSuggestGate() centralises the guest-side allow/block check
shared between useOrbitSongRowBehavior and the ContextMenu Add-to-Session
items, plus suggestOrbitTrack as a defensive last line.

i18n: en + de + fr + nl + zh + nb + ru + es.

Also fixes an earlier dedupe-key collision: the (user, trackId) cache
keys were missing their separator (NULL byte slipped in during the
previous patch), so two tracks could share a key and one of them
silently overwrite the other. Restored the space separator.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/locales/zh.ts

@@ -1554,6 +1554,10 @@ export const zhTranslation = {
     participantsRemoveAria: '从此会话中移除 {{user}}',
     participantsBanTooltip: '永久封禁',
     participantsBanAria: '永久封禁 {{user}}',
+    participantsMuteTooltip: '禁止投歌',
+    participantsUnmuteTooltip: '允许投歌',
+    participantsMuteAria: '禁止 {{user}} 投歌',
+    participantsUnmuteAria: '允许 {{user}} 重新投歌',
     confirmRemoveTitle: '从会话中移除？',
     confirmRemoveBody: '{{user}} 将从会话中移除，但可以通过你的邀请链接重新加入。',
     confirmRemoveConfirm: '移除',
@@ -1579,6 +1583,12 @@ export const zhTranslation = {
     settingAutoShuffleHint: '即将播放队列的定期 Fisher-Yates 洗牌。关闭：顺序仅在你手动重新排列时改变。',
     settingShuffleInterval: '洗牌间隔',
     settingShuffleIntervalHint: '会话运行时即将播放队列的重新洗牌频率。',
+    settingMaxPending: '最大待审投歌数',
+    settingMaxPendingHint: '同时等待审核的访客投歌上限。0 = 不限制。',
+    pendingCounter: '{{count}} / {{max}} 待审',
+    pendingCounterTooltip: '等待中的访客投歌 / 上限',
+    suggestBlockedMuted: '主持人已禁止你在本场会话投歌。',
+    suggestBlockedCap: '审核队列已满，等主持人处理一些再继续。',
     settingShuffleIntervalValue_one: '{{count}} 分钟',
     settingShuffleIntervalValue_other: '{{count}} 分钟',
     settingShuffleNow: '立即洗牌',