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>

backend/migrations/versions/009_project_health_table.py

@@ -0,0 +1,42 @@
+"""Create project health table
+
+Revision ID: 009
+Revises: 008
+Create Date: 2025-01-04
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision = '009'
+down_revision = '008'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # Create project_health table
+    op.create_table(
+        'pjctrl_project_health',
+        sa.Column('id', sa.String(36), primary_key=True),
+        sa.Column('project_id', sa.String(36), sa.ForeignKey('pjctrl_projects.id', ondelete='CASCADE'), nullable=False, unique=True),
+        sa.Column('health_score', sa.Integer, server_default='100', nullable=False),
+        sa.Column('risk_level', sa.Enum('low', 'medium', 'high', 'critical', name='risk_level_enum'), server_default='low', nullable=False),
+        sa.Column('schedule_status', sa.Enum('on_track', 'at_risk', 'delayed', name='schedule_status_enum'), server_default='on_track', nullable=False),
+        sa.Column('resource_status', sa.Enum('adequate', 'constrained', 'overloaded', name='resource_status_enum'), server_default='adequate', nullable=False),
+        sa.Column('last_updated', sa.DateTime, server_default=sa.func.now(), nullable=False),
+    )
+
+    # Create indexes
+    op.create_index('idx_project_health_project', 'pjctrl_project_health', ['project_id'])
+    op.create_index('idx_project_health_risk', 'pjctrl_project_health', ['risk_level'])
+
+
+def downgrade() -> None:
+    op.drop_index('idx_project_health_risk', table_name='pjctrl_project_health')
+    op.drop_index('idx_project_health_project', table_name='pjctrl_project_health')
+    op.drop_table('pjctrl_project_health')
+    op.execute("DROP TYPE IF EXISTS risk_level_enum")
+    op.execute("DROP TYPE IF EXISTS schedule_status_enum")
+    op.execute("DROP TYPE IF EXISTS resource_status_enum")