fix: 撤回 typewriter 改动，novel 改用直接累加 delta 保证流式输出

之前用 useTypewriterStream.writer.push + 同步读 visibleText 有时序问题：
writer 的 visibleText 由内部 setInterval 异步推进，push 后立即同步读得到空串，
气泡一直空白。

撤回 typewriter 改动，恢复 novel_delta 直接 lastNovel.content += delta，
SSE 本身就是流式推送，每次到达即显示。

保留 confirmOutline / modifyOutline 的 pendingNextResponse = true 修复（loading）。

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

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

@@ -290,8 +290,6 @@ const currentVersionMessageId = ref('')
 const novelSessionId = ref('')
 const novelFullText = ref('')
 const novelOutline = ref(null)
-// novel 消息 id → typewriter writer 实例映射（用于真正的逐字流式输出）
-const novelWriters = new Map()
 const clarificationCard = ref(null)
 const currentStreamTask = ref(null)
 const answeringClarification = ref(false)
@@ -1707,27 +1705,16 @@ const handleShortNovelEvent = (event) => {
       generationStatus.value = 'idle'
       pendingNextResponse.value = false
       break
-    case 'novel_start': {
+    case 'novel_start':
-      const novelMsg = addResultMessage({ role: 'assistant', kind: 'novel', content: '', pending: true })
+      addResultMessage({ role: 'assistant', kind: 'novel', content: '', pending: true })
-      // 为这条 novel 消息创建独立的 typewriter writer，实现逐字流式输出
-      novelWriters.set(novelMsg.id, useTypewriterStream({ interval: 32, step: 1 }))
       generationStatus.value = 'streaming'
       pendingNextResponse.value = false
       break
-    }
     case 'novel_delta': {
-      // 往最后一条 pending novel 消息推送 delta 到 typewriter writer
+      // 往最后一条 pending novel 消息直接累加 delta，保证流式显示
       const lastNovel = [...resultMessages.value].reverse().find(m => m.kind === 'novel' && m.pending)
       if (lastNovel) {
-        const writer = novelWriters.get(lastNovel.id)
+        lastNovel.content += payload.delta || ''
-        const delta = payload.delta || ''
-        if (writer) {
-          writer.push((writer.targetText?.value || '') + delta)
-          lastNovel.content = writer.visibleText.value
-          // writer 的 visibleText 是 reactive，需用 watch；但这里直接读取值即可
-        } else {
-          lastNovel.content += delta
-        }
       }
       keepResultAtBottom()
       break
@@ -1736,17 +1723,7 @@ const handleShortNovelEvent = (event) => {
       // 标记最后一条 novel 消息完成
       const lastNovel = [...resultMessages.value].reverse().find(m => m.kind === 'novel')
       if (lastNovel) {
-        const writer = novelWriters.get(lastNovel.id)
+        if (payload.full_text) lastNovel.content = payload.full_text
-        const finalText = payload.full_text || ''
-        if (writer) {
-          writer.finish(finalText)
-          // finish 后 typewriter 会逐字排空到 targetText，等排空完成再写回 content
-          // 但为了持久化和立即显示，这里直接同步设值
-          lastNovel.content = finalText
-          novelWriters.delete(lastNovel.id)
-        } else if (finalText) {
-          lastNovel.content = finalText
-        }
         lastNovel.pending = false
       }
       scriptId.value = payload.scriptId || ''