feat: complete issue fixes and implement remaining features

## Critical Issues (CRIT-001~003) - All Fixed
- JWT secret key validation with pydantic field_validator
- Login audit logging for success/failure attempts
- Frontend API path prefix removal

## High Priority Issues (HIGH-001~008) - All Fixed
- Project soft delete using is_active flag
- Redis session token bytes handling
- Rate limiting with slowapi (5 req/min for login)
- Attachment API permission checks
- Kanban view with drag-and-drop
- Workload heatmap UI (WorkloadPage, WorkloadHeatmap)
- TaskDetailModal integrating Comments/Attachments
- UserSelect component for task assignment

## Medium Priority Issues (MED-001~012) - All Fixed
- MED-001~005: DB commits, N+1 queries, datetime, error format, blocker flag
- MED-006: Project health dashboard (HealthService, ProjectHealthPage)
- MED-007: Capacity update API (PUT /api/users/{id}/capacity)
- MED-008: Schedule triggers (cron parsing, deadline reminders)
- MED-009: Watermark feature (image/PDF watermarking)
- MED-010~012: useEffect deps, DOM operations, PDF export

## New Files
- backend/app/api/health/ - Project health API
- backend/app/services/health_service.py
- backend/app/services/trigger_scheduler.py
- backend/app/services/watermark_service.py
- backend/app/core/rate_limiter.py
- frontend/src/pages/ProjectHealthPage.tsx
- frontend/src/components/ProjectHealthCard.tsx
- frontend/src/components/KanbanBoard.tsx
- frontend/src/components/WorkloadHeatmap.tsx

## Tests
- 113 new tests passing (health: 32, users: 14, triggers: 35, watermark: 32)

## OpenSpec Archives
- add-project-health-dashboard
- add-capacity-update-api
- add-schedule-triggers
- add-watermark-feature
- add-rate-limiting
- enhance-frontend-ux
- add-resource-management-ui

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

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

openspec/changes/archive/2026-01-04-add-project-health-dashboard/proposal.md

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+# Change: Add Project Health Dashboard
+
+## Why
+MED-006: The `Multi-Project Health Dashboard` requirement exists in the spec but has no implementation. Managers cannot view an overview of all projects' health status, making it difficult to identify at-risk projects.
+
+## What Changes
+- Add `pjctrl_project_health` database table and migration
+- Implement backend API endpoints for project health data
+- Create frontend Project Health Dashboard page
+- Add health score calculation service
+
+## Impact
+- Affected specs: resource-management
+- Affected code:
+  - `backend/app/models/project_health.py` (new)
+  - `backend/app/api/health/router.py` (new)
+  - `backend/app/services/health_service.py` (new)
+  - `frontend/src/pages/ProjectHealthPage.tsx` (new)

openspec/changes/archive/2026-01-04-add-project-health-dashboard/specs/resource-management/spec.md

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+## MODIFIED Requirements
+
+### Requirement: Multi-Project Health Dashboard
+系統 SHALL 提供多專案健康看板，讓主管一覽所有專案狀態。
+
+#### Scenario: 專案健康總覽
+- **GIVEN** 主管負責多個專案
+- **WHEN** 主管開啟健康看板
+- **THEN** 顯示所有專案的進度、風險指標、延遲任務數
+- **AND** 可依風險程度排序
+
+#### Scenario: 專案延遲警示
+- **GIVEN** 專案有任務超過截止日期
+- **WHEN** 主管查看健康看板
+- **THEN** 該專案標示為延遲狀態
+- **AND** 顯示延遲任務數量與影響
+
+#### Scenario: 專案健康 API
+- **GIVEN** 後端系統運行中
+- **WHEN** 客戶端請求 `GET /api/projects/health`
+- **THEN** 系統回傳所有可存取專案的健康數據
+- **AND** 包含 `total_tasks`, `completed_tasks`, `overdue_tasks`, `blocked_tasks`, `risk_score`
+
+#### Scenario: 單一專案健康詳情
+- **GIVEN** 主管需要查看特定專案詳情
+- **WHEN** 客戶端請求 `GET /api/projects/{id}/health`
+- **THEN** 系統回傳該專案的詳細健康數據
+- **AND** 包含任務分類統計與風險評估

openspec/changes/archive/2026-01-04-add-project-health-dashboard/tasks.md

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+# Tasks: add-project-health-dashboard
+
+## Phase 1: Backend - Database & Model
+
+- [x] 1.1 Create ProjectHealth model (`backend/app/models/project_health.py`)
+- [x] 1.2 Create Alembic migration for `pjctrl_project_health` table
+- [x] 1.3 Create ProjectHealth schemas (`backend/app/schemas/project_health.py`)
+
+## Phase 2: Backend - Service & API
+
+- [x] 2.1 Create HealthService class (`backend/app/services/health_service.py`)
+  - Calculate risk score based on overdue/blocked tasks
+  - Aggregate project statistics
+- [x] 2.2 Create health router (`backend/app/api/health/router.py`)
+- [x] 2.3 Implement `GET /api/projects/health` - List all projects health
+- [x] 2.4 Implement `GET /api/projects/{id}/health` - Single project health
+- [x] 2.5 Register health router in main.py
+
+## Phase 3: Backend - Testing
+
+- [x] 3.1 Unit tests for HealthService
+- [x] 3.2 API endpoint tests
+
+## Phase 4: Frontend - UI Components
+
+- [x] 4.1 Create ProjectHealthPage.tsx
+- [x] 4.2 Create ProjectHealthCard component
+- [x] 4.3 Add route to App.tsx
+- [x] 4.4 Add navigation link in Layout
+
+## Validation Criteria
+
+- Risk score correctly reflects overdue and blocked tasks
+- Dashboard shows all accessible projects
+- Color-coded status indicators (green/yellow/red)