feat(mini-program): ScriptView 恢复小说消息操作按钮组

- 为 kind === 'novel' 的消息添加折叠/展开、复制、播放按钮
- 复用已有函数：getMessageDisplayContent、toggleMessageCollapse、copyMessageContent、playMessageTts
- 折叠按钮条件改用 ASSISTANT_MESSAGE_PREVIEW_LENGTH 常量（替代硬编码 120）
- 添加 .collapse-toggle-row、.message-actions、.action-btn 样式
- 修复 openScriptChat：payload 只有 id 时从 store 获取完整 script 数据，避免 conversationId 缺失导致 loadMessages 不调用
- H5 验收通过：复制/播放/折叠/展开功能正常

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mini-program/src/pages/main/ScriptView.vue

@@ -183,7 +183,28 @@
               </view>
 
               <view v-else-if="msg.kind === 'novel'" class="chat-bubble system">
-                <text class="novel-text">{{ msg.content }}<text v-if="msg.pending" class="typing-cursor">|</text></text>
+                <text class="novel-text">{{ getMessageDisplayContent(msg) }}</text>
+                <text v-if="msg.pending && !isMessageCollapsed(msg)" class="typing-cursor">|</text>
+
+                <!-- 折叠/展开按钮（内容超过预览长度时显示） -->
+                <view v-if="msg.content && msg.content.length > ASSISTANT_MESSAGE_PREVIEW_LENGTH" class="collapse-toggle-row" @click="toggleMessageCollapse(msg)">
+                  <text class="collapse-toggle-text">{{ isMessageCollapsed(msg) ? '展开全文' : '收起全文' }}</text>
+                  <view class="collapse-chevron" :class="{ down: isMessageCollapsed(msg) }">
+                    <view></view>
+                    <view></view>
+                  </view>
+                </view>
+
+                <!-- 操作按钮组（仅在非 pending 状态显示） -->
+                <view v-if="!msg.pending" class="message-actions">
+                  <button class="action-btn" @click="copyMessageContent(msg)">
+                    <text>复制</text>
+                  </button>
+                  <button class="action-btn primary" @click="playMessageTts(msg)">
+                    <text class="action-icon">{{ ttsPlayer.playing.value ? 'Ⅱ' : '▶' }}</text>
+                    <text>{{ ttsPlayer.playing.value ? '暂停' : '播放' }}</text>
+                  </button>
+                </view>
               </view>
 
               <view v-else class="chat-bubble system">
@@ -1444,7 +1465,10 @@ const normalizeGeneratedContent = (text) => {
 const openScriptChat = async (payload = {}) => {
   uni.removeStorageSync(PENDING_SCRIPT_CHAT_KEY)
   const scriptIdParam = String(payload?.id || payload?.scriptId || '')
-  let script = payload?.script || (payload?.id ? payload : null)
+  // 优先使用 payload 中携带的完整 script 对象；否则按 id 从 store 取完整数据
+  // 修复：payload 只有 id 时，直接用 payload 会导致 conversationId/plotJson 等字段缺失，
+  // 进而 loadMessages 不会被调用，详情页内容为空
+  let script = payload?.script || null
   if (!script?.id && scriptIdParam) {
     script = store.getScriptById(scriptIdParam)
     if (!script) {
@@ -4069,4 +4093,107 @@ onUnmounted(() => {
   50% { opacity: 0; }
 }
 
+/* 折叠/展开按钮行 */
+.collapse-toggle-row {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 12rpx;
+  margin-top: 20rpx;
+  padding: 16rpx 0;
+  border-radius: 999rpx;
+  background: rgba(88, 28, 135, 0.12);
+  border: 1rpx solid rgba(192, 132, 252, 0.28);
+  color: rgba(246, 230, 255, 0.96);
+  font-size: 26rpx;
+  font-weight: 700;
+}
+
+.collapse-toggle-row:active {
+  transform: scale(0.98);
+  opacity: 0.92;
+}
+
+.collapse-toggle-text {
+  line-height: 1;
+}
+
+/* 折叠箭头图标 */
+.collapse-chevron {
+  position: relative;
+  width: 20rpx;
+  height: 16rpx;
+  flex-shrink: 0;
+  transition: transform 0.18s ease;
+}
+
+.collapse-chevron.down {
+  transform: rotate(180deg);
+}
+
+.collapse-chevron view {
+  position: absolute;
+  top: 7rpx;
+  width: 12rpx;
+  height: 4rpx;
+  border-radius: 999rpx;
+  background: linear-gradient(90deg, #fff3b0, #ffd86b);
+  box-shadow: 0 0 12rpx rgba(255, 216, 107, 0.5);
+}
+
+.collapse-chevron view:first-child {
+  left: 0;
+  transform: rotate(-38deg);
+  transform-origin: right center;
+}
+
+.collapse-chevron view:last-child {
+  right: 0;
+  transform: rotate(38deg);
+  transform-origin: left center;
+}
+
+/* 操作按钮组 */
+.message-actions {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 14rpx;
+  margin-top: 20rpx;
+}
+
+.action-btn {
+  height: 72rpx;
+  min-height: 72rpx;
+  padding: 0 8rpx;
+  border-radius: 28rpx;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  color: #e8ccff;
+  font-size: 26rpx;
+  font-weight: 700;
+  line-height: 1.15;
+  text-align: center;
+  white-space: normal;
+  box-sizing: border-box;
+  background: rgba(88, 28, 135, 0.18);
+  border: 1rpx solid rgba(192, 132, 252, 0.35);
+}
+
+.action-btn.primary {
+  color: #fff;
+  background: linear-gradient(145deg, #8c44f2, #5f1db8);
+}
+
+.action-icon {
+  margin-right: 8rpx;
+  font-size: 24rpx;
+  font-weight: 900;
+  line-height: 1;
+}
+
+.action-btn::after {
+  border: 0;
+}
+
 </style>