feat: enhance weekly report and realtime notifications

Weekly Report (fix-weekly-report):
- Remove 5-task limit, show all tasks per category
- Add blocked tasks with blocker_reason and blocked_since
- Add next week tasks (due in coming week)
- Add assignee_name, completed_at, days_overdue to task details
- Frontend collapsible sections for each task category
- 8 new tests for enhanced report content

Realtime Notifications (fix-realtime-notifications):
- SQLAlchemy event-based notification publishing
- Redis Pub/Sub for multi-process broadcast
- Fix soft rollback handler stacking issue
- Fix ping scheduling drift (send immediately when interval expires)
- Frontend NotificationContext with WebSocket reconnection

Spec Fixes:
- Add missing ## Purpose sections to 5 specs

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

openspec/changes/archive/2025-12-30-fix-weekly-report/design.md

@@ -0,0 +1,119 @@
+## Context
+
+automation spec 定義週報須包含：已完成、進行中、逾期、阻礙中、下週預計任務清單。現行實作僅提供數量統計與部分摘要。
+
+## Goals / Non-Goals
+
+**Goals:**
+- 週報內容包含完整任務清單
+- 新增阻礙中任務清單
+- 新增下週預計完成任務清單
+
+**Non-Goals:**
+- 不實作週報自訂欄位篩選
+- 不實作週報匯出 PDF/Excel
+
+## Decisions
+
+### 1. 週報內容結構
+
+**Decision:** 擴充 content JSON 結構
+
+**Current:**
+```json
+{
+  "summary": { "completed_count": 5, "in_progress_count": 3, ... },
+  "projects": [
+    {
+      "completed_tasks": [{"id": "...", "title": "..."}],  // 限制 5 筆
+      "overdue_tasks": [...]  // 限制 5 筆
+    }
+  ]
+}
+```
+
+**Proposed:**
+```json
+{
+  "summary": {
+    "completed_count": 5,
+    "in_progress_count": 3,
+    "overdue_count": 2,
+    "blocked_count": 1,
+    "next_week_count": 4,
+    "total_tasks": 15
+  },
+  "projects": [
+    {
+      "project_id": "uuid",
+      "project_title": "Project Name",
+      "completed_tasks": [
+        {"id": "...", "title": "...", "completed_at": "ISO8601", "assignee_name": "..."}
+      ],
+      "in_progress_tasks": [
+        {"id": "...", "title": "...", "assignee_name": "...", "due_date": "ISO8601"}
+      ],
+      "overdue_tasks": [
+        {"id": "...", "title": "...", "due_date": "ISO8601", "days_overdue": 3}
+      ],
+      "blocked_tasks": [
+        {"id": "...", "title": "...", "blocker_reason": "...", "blocked_since": "ISO8601"}
+      ],
+      "next_week_tasks": [
+        {"id": "...", "title": "...", "due_date": "ISO8601", "assignee_name": "..."}
+      ]
+    }
+  ]
+}
+```
+
+### 2. 阻礙任務識別
+
+**Decision:** 查詢 Blocker 表關聯
+
+```python
+# 取得有未解除阻礙的任務
+blocked_task_ids = db.query(Blocker.task_id).filter(
+    Blocker.resolved_at.is_(None)
+).subquery()
+
+blocked_tasks = db.query(Task).filter(
+    Task.project_id.in_(project_ids),
+    Task.id.in_(blocked_task_ids)
+).all()
+```
+
+### 3. 下週預計任務
+
+**Decision:** due_date 在下週一至週日
+
+```python
+next_week_start = week_end  # 本週末 = 下週初
+next_week_end = next_week_start + timedelta(days=7)
+
+next_week_tasks = db.query(Task).filter(
+    Task.project_id.in_(project_ids),
+    Task.due_date >= next_week_start,
+    Task.due_date < next_week_end,
+    Task.status.not_in(["done", "completed"])
+).all()
+```
+
+### 4. 任務明細欄位
+
+**Decision:** 包含以下欄位供顯示
+
+| 任務類型 | 額外欄位 |
+|---------|---------|
+| completed | completed_at (updated_at), assignee_name |
+| in_progress | assignee_name, due_date |
+| overdue | due_date, days_overdue |
+| blocked | blocker_reason, blocked_since |
+| next_week | due_date, assignee_name |
+
+## Risks / Trade-offs
+
+| Risk | Mitigation |
+|------|------------|
+| 大量任務導致 content JSON 過大 | 評估後續加入分頁或限制 |
+| 阻礙查詢需 JOIN | 使用 subquery 減少 N+1 |