修复: 全栈审查 FR-C1~C5 五项正确性 bug

- FR-C1 formattedEvents 时间漂移:事件入数组固 _ts 时间戳(project.ts push + ProjectDetail 用 _ts)，computed 重算不再刷历史时间为当前时刻
- FR-C2 sentiment 三档统一:模板 >0/<0/===0 + sentimentClass 同源 + i18n neutral(zh/en)，原模板>0 与 class>=0 矛盾
- FR-C3 Settings timer 泄漏:onUnmounted 清全部三个(原仅 _concurrencyTimer)
- FR-C4 MIGRATION_VERSION 死常量:删(零代码引用,run() if 链自管版本)
- FR-C5 AiConversationDetail 缺 readonly:加 readonly?: boolean(后端 generating 时返回)
来源 fullstack-review §3(已核实);cargo/vue-tsc 0 err

src/views/Ideas.vue

@@ -100,7 +100,7 @@
               </div>
               <p class="final-score">{{ $t('ideas.finalScore', { score: adversarialEval.final_score.toFixed(1) }) }}</p>
               <div class="net-sentiment" :class="sentimentClass(adversarialEval.net_sentiment)">
-                {{ $t('ideas.netSentiment', { tone: adversarialEval.net_sentiment > 0 ? $t('ideas.sentimentPositive') : $t('ideas.sentimentNegative'), n: (adversarialEval.net_sentiment * 100).toFixed(0) }) }}
+                {{ $t('ideas.netSentiment', { tone: adversarialEval.net_sentiment > 0 ? $t('ideas.sentimentPositive') : (adversarialEval.net_sentiment < 0 ? $t('ideas.sentimentNegative') : $t('ideas.sentimentNeutral')), n: (adversarialEval.net_sentiment * 100).toFixed(0) }) }}
               </div>
               <p class="summary">{{ adversarialEval.analyst.summary }}</p>
             </div>
@@ -366,7 +366,10 @@ function assessmentLabel(recommendation: string) {
 }
 
 function sentimentClass(sentiment: number) {
-  return sentiment >= 0 ? 'positive' : 'negative'
+  // 统一三档(FR-C2: 原 >=0 与模板 >0 矛盾，net_sentiment=0 时文案负面样式 positive)
+  if (sentiment > 0) return 'positive'
+  if (sentiment < 0) return 'negative'
+  return 'neutral'
 }
 
 function scoreClass(score: number | null) {