修复会议详情页响应会议后toast文案"已已接受"/"已已拒绝"重复"已"字

MeetingDetail.respond()提交回应成功后用 `已${RESPONSE_LABEL[response]}` 拼toast文案，
但RESPONSE_LABEL的accepted/declined两项本身已经是"已接受"/"已拒绝"（给参与人列表
徽标用的），再拼一次"已"前缀就变成"已已接受"/"已已拒绝"；tentative没有"已"前缀，
拼出来是"已待定"，语义也不通顺。同页面另一个响应入口MeetingCard.respond()
早就手写了三条正确文案（已接受会议邀请/已拒绝会议邀请/已标记为待定），
两处本应一致却各写一套。

改为复用MeetingCard已有的正确文案，不再从RESPONSE_LABEL派生。

已用kcg051307发起、asn494180作为参会人的3场真实会议在浏览器逐一实测三种回应，
确认toast分别正确显示"已接受会议邀请"/"已拒绝会议邀请"/"已标记为待定"。

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/views/workplace-collaboration-view.jsx

@@ -400,8 +400,15 @@ function MeetingDetail({hashParams, onToast}) {
   };
   const respond = response => {
     setBusy(true);
+    // Live-repro'd (round 14): RESPONSE_LABEL's 'accepted'/'declined' entries are already prefixed
+    // ("已接受"/"已拒绝") for use as the disabled-button/participant-badge label elsewhere on this
+    // page -- reusing it here with an extra literal "已" in front produced a toast reading "已已接受"/
+    // "已已拒绝" (and a slightly-off "已待定" for tentative, since that entry has no "已" to double up
+    // with). MeetingCard's own respond() (this same action, reached from the list card instead of this
+    // detail page) already had correct, un-doubled wording for all three -- reuse that instead of
+    // re-deriving new strings from RESPONSE_LABEL.
     getMeeting(meeting.meeting_id).then(fresh => respondMeeting(fresh.meeting_id, response, fresh.version))
-      .then(_ => { onToast(RESPONSE_LABEL[response] ? `已${RESPONSE_LABEL[response]}` : '已回应'); load(); })
+      .then(_ => { onToast(response === 'accepted' ? '已接受会议邀请' : response === 'declined' ? '已拒绝会议邀请' : '已标记为待定'); load(); })
       .catch(err => onToast(err.message || '操作失败')).finally(() => setBusy(false));
   };