feat: implement automation module

- Event-based triggers (Phase 1):
  - Trigger/TriggerLog models with field_change type
  - TriggerService for condition evaluation and action execution
  - Trigger CRUD API endpoints
  - Task integration (status, assignee, priority changes)
  - Frontend: TriggerList, TriggerForm components

- Weekly reports (Phase 2):
  - ScheduledReport/ReportHistory models
  - ReportService for stats generation
  - APScheduler for Friday 16:00 job
  - Report preview/generate/history API
  - Frontend: WeeklyReportPreview, ReportHistory components

- Tests: 23 new tests (14 triggers + 9 reports)
- OpenSpec: add-automation change archived

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

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

openspec/changes/archive/2025-12-29-add-automation/specs/automation/spec.md

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+## MODIFIED Requirements
+
+### Requirement: Trigger-Based Automation
+系統 SHALL 支援觸發器 (Triggers)，當特定條件滿足時自動執行動作。
+
+#### Scenario: 狀態變更觸發通知
+- **GIVEN** 專案設定了「當任務狀態變更為待測試時，通知指派者」的觸發器
+- **WHEN** 任務狀態變更為「待測試」
+- **THEN** 系統自動發送通知給任務指派者
+- **AND** 觸發器執行記錄至 TriggerLog
+
+#### Scenario: 建立觸發器
+- **GIVEN** 專案管理者需要建立自動化規則
+- **WHEN** 管理者透過 API 設定觸發條件與動作
+- **THEN** 系統儲存觸發器規則
+- **AND** 規則立即生效
+
+### Requirement: Trigger Conditions
+系統 SHALL 支援欄位變更觸發條件。
+
+#### Scenario: 欄位變更條件
+- **GIVEN** 觸發器設定為「當 status_id 欄位變更為特定值」
+- **WHEN** 任務的 status_id 欄位變更為該值
+- **THEN** 觸發器被觸發
+- **AND** 支援運算子: equals, not_equals, changed_to, changed_from
+
+### Requirement: Trigger Actions
+系統 SHALL 支援發送通知動作。
+
+#### Scenario: 發送通知動作
+- **GIVEN** 觸發器動作設定為 notify
+- **WHEN** 觸發器被觸發
+- **THEN** 系統使用 NotificationService 發送通知
+- **AND** 通知目標支援: assignee, creator, project_owner, user:<id>
+- **AND** 通知內容可使用變數模板
+
+### Requirement: Automated Weekly Report
+系統 SHALL 每週五下午 4:00 自動彙整本週任務狀態發送給主管。
+
+#### Scenario: 週報自動生成
+- **GIVEN** APScheduler 排程設定為每週五 16:00
+- **WHEN** 到達排程時間
+- **THEN** ReportService 彙整使用者所屬專案的任務狀態
+- **AND** 生成週報並透過 NotificationService 發送
+
+#### Scenario: 週報內容
+- **GIVEN** 週報生成中
+- **WHEN** 系統彙整資料
+- **THEN** 週報 JSON 包含：
+  - completed_count: 本週已完成任務數
+  - in_progress_count: 進行中任務數
+  - overdue_count: 逾期任務數
+  - tasks: 詳細任務清單
+
+## MODIFIED Data Model
+
+```
+pjctrl_triggers
+├── id: UUID (PK)
+├── project_id: UUID (FK -> projects)
+├── name: VARCHAR(200)
+├── description: TEXT
+├── trigger_type: ENUM('field_change', 'schedule')
+├── conditions: JSON
+│   └── { "field": "status_id", "operator": "changed_to", "value": "uuid" }
+├── actions: JSON
+│   └── [{ "type": "notify", "target": "assignee", "template": "..." }]
+├── is_active: BOOLEAN DEFAULT true
+├── created_by: UUID (FK -> users)
+├── created_at: TIMESTAMP
+└── updated_at: TIMESTAMP
+
+pjctrl_trigger_logs
+├── id: UUID (PK)
+├── trigger_id: UUID (FK -> triggers)
+├── task_id: UUID (FK -> tasks, nullable)
+├── executed_at: TIMESTAMP
+├── status: ENUM('success', 'failed')
+├── details: JSON
+└── error_message: TEXT
+
+pjctrl_scheduled_reports
+├── id: UUID (PK)
+├── report_type: ENUM('weekly')
+├── recipient_id: UUID (FK -> users)
+├── is_active: BOOLEAN DEFAULT true
+├── last_sent_at: TIMESTAMP
+└── created_at: TIMESTAMP
+
+pjctrl_report_history
+├── id: UUID (PK)
+├── report_id: UUID (FK -> scheduled_reports)
+├── generated_at: TIMESTAMP
+├── content: JSON
+├── status: ENUM('sent', 'failed')
+└── error_message: TEXT
+```
+
+## MODIFIED Technical Notes
+
+- 使用 APScheduler (AsyncIOScheduler) 處理排程任務，嵌入 FastAPI 應用內運行
+- 觸發器評估採用同步處理，任務更新時直接執行，避免複雜的異步處理
+- 所有觸發器執行都記錄至 TriggerLog 供追蹤
+- Phase 1 僅支援 notify 動作
+- 條件運算子: equals, not_equals, changed_to, changed_from