fix: 计划任务勾选逻辑 + 胶囊进度计算修正

1. 必须点击"开始"后才能勾选任务：
   - 调研/产品方案/UI设计的 checkbox 加 disabled 判断
   - plan.status !== 'in_progress' 时不可交互

2. 调研勾选改为二态（与产品/UI一致）：
   - 去掉三态循环（pending→in_progress→completed）
   - 改为 toggle：未完成 ↔ 已完成
   - 显示文字也简化为"已完成"/"未完成"

3. 胶囊进度百分比计算修正：
   - 旧逻辑：所有子任务合并计算（新建空任务导致分母为0返回0%）
   - 新逻辑：以 plan 为单位加权计算
     - completed 的 plan = 权重 1
     - in_progress 的 plan = 子任务完成率
     - pending 的 plan = 权重 0
   - 公式：sum(weights) / plan_count * 100
   - 新建一个 pending 的 plan 不会把已完成的 100% 打回 0%

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

apps/web/app/versions/[id]/page.tsx

@@ -303,23 +303,27 @@ export default function VersionDetailPage() {
 
                   const calcGroupProgress = (group: typeof vPlans, type: 'research' | 'product' | 'ui') => {
                     if (group.length === 0) return 0;
-                    if (type === 'research') {
-                      const totals = group.reduce((acc, p) => {
-                        const tasks = p.tasks || [];
-                        acc.total += tasks.length;
-                        acc.done += tasks.filter((t) => t.status === 'completed').length;
-                        return acc;
-                      }, { total: 0, done: 0 });
-                      return totals.total > 0 ? Math.round((totals.done / totals.total) * 100) : 0;
+                    // 每个 plan 按权重贡献进度：completed=1, in_progress=子任务完成率, pending=0
+                    let totalWeight = 0;
+                    for (const p of group) {
+                      if (p.status === 'completed') {
+                        totalWeight += 1;
+                      } else if (p.status === 'in_progress') {
+                        if (type === 'research') {
+                          const tasks = p.tasks || [];
+                          if (tasks.length > 0) {
+                            totalWeight += tasks.filter((t) => t.status === 'completed').length / tasks.length;
+                          }
+                        } else {
+                          const linked = p.linkedRequirementIds || [];
+                          const completed = p.completedRequirementIds || [];
+                          if (linked.length > 0) {
+                            totalWeight += completed.filter((id) => linked.includes(id)).length / linked.length;
+                          }
+                        }
+                      }
                     }
-                    const totals = group.reduce((acc, p) => {
-                      const linked = p.linkedRequirementIds || [];
-                      const completed = p.completedRequirementIds || [];
-                      acc.total += linked.length;
-                      acc.done += completed.filter((id) => linked.includes(id)).length;
-                      return acc;
-                    }, { total: 0, done: 0 });
-                    return totals.total > 0 ? Math.round((totals.done / totals.total) * 100) : 0;
+                    return Math.round((totalWeight / group.length) * 100);
                   };
 
                   const getPlanStatus = (group: typeof vPlans): 'idle' | 'active' | 'done' => {