feat(phase-5): implement comprehensive Markdown and PDF report export system

�� Advanced Report Generation:
- Complete Handlebars templating system for professional reports
- Markdown report generator with embedded Mermaid diagrams
- PDF report generator using Puppeteer with server-side rendering
- Comprehensive analysis data integration from all phases

🎨 Professional Report Design:
- Beautiful PDF layouts with proper typography and spacing
- Responsive design for print and digital viewing
- Visual Mermaid flowcharts for redirect chain visualization
- Color-coded status badges and comprehensive data tables

📊 Rich Report Content:
- Complete redirect chain analysis with hop-by-hop details
- SSL certificate analysis with expiry and security warnings
- SEO optimization recommendations and meta tag analysis
- Security vulnerability findings and mixed content detection
- Performance metrics with latency visualization

🔧 Export Service Architecture:
- Dedicated ExportService class with comprehensive error handling
- Professional Handlebars helpers for date, duration, and URL formatting
- Automatic Mermaid diagram generation from redirect hop data
- File system management with cleanup and temporary file handling

🌐 RESTful Export API:
- GET /api/v2/export/:checkId/markdown - Generate Markdown reports
- GET /api/v2/export/:checkId/pdf - Generate PDF reports with embedded charts
- POST /api/v2/export/:checkId/save - Save reports to filesystem (authenticated)
- GET /api/v2/export/formats - Discover available export formats
- DELETE /api/v2/export/cleanup - Clean up old report files

🔒 Security and Rate Limiting:
- Enhanced rate limiting for resource-intensive export operations (20/hour)
- Proper authentication for save operations and admin functions
- Comprehensive input validation with Zod schemas
- Security headers for PDF downloads and XSS protection

📋 Template System:
- Professional Markdown template with comprehensive sections
- HTML template for PDF generation with embedded CSS and JavaScript
- Mermaid diagram integration with automatic chart generation
- Organization branding support and customizable layouts

⚡ Performance Optimizations:
- Puppeteer configuration optimized for headless server environments
- Efficient template compilation and caching
- Background processing ready for resource-intensive operations
- Proper memory management for large report generations

🛠️ Development Features:
- Comprehensive test suite for all export functionality
- Graceful error handling with detailed error messages
- Proper MIME type detection and content headers
- Download functionality with custom filenames

Requirements: Node.js 18+ for Puppeteer, Handlebars templating, Mermaid rendering

apps/api/package.json

@@ -30,7 +30,13 @@
     "compression": "^1.7.4",
     "dotenv": "^16.3.1",
     "jsdom": "^23.0.1",
-    "winston": "^3.11.0"
+    "winston": "^3.11.0",
+    "puppeteer": "^21.9.0",
+    "handlebars": "^4.7.8",
+    "mermaid": "^10.6.1",
+    "markdown-it": "^14.0.0",
+    "file-type": "^19.0.0",
+    "mime-types": "^2.1.35"
   },
   "devDependencies": {
     "@types/express": "^4.17.21",
@@ -46,6 +52,9 @@
     "@types/jest": "^29.5.8",
     "ts-jest": "^29.1.1",
     "supertest": "^6.3.3",
-    "@types/supertest": "^2.0.16"
+    "@types/supertest": "^2.0.16",
+    "@types/puppeteer": "^7.0.4",
+    "@types/markdown-it": "^13.0.7",
+    "@types/mime-types": "^2.1.4"
   }
 }