Add production WSGI server - Flask dev server unsuitable for production load

This adds a complete production deployment setup using Gunicorn as the WSGI server, replacing Flask's development server.

Key components:
- Gunicorn configuration with optimized worker settings
- Support for sync, threaded, and async (gevent) workers
- Automatic worker recycling to prevent memory leaks
- Increased timeouts for audio processing
- Production-ready logging and monitoring

Deployment options:
1. Docker/Docker Compose for containerized deployment
2. Systemd service for traditional deployment
3. Nginx reverse proxy configuration
4. SSL/TLS support

Production features:
- wsgi.py entry point for WSGI servers
- gunicorn_config.py with production settings
- Dockerfile with multi-stage build
- docker-compose.yml with full stack (Redis, PostgreSQL)
- nginx.conf with caching and security headers
- systemd service with security hardening
- deploy.sh automated deployment script

Configuration:
- .env.production template with all settings
- Support for environment-based configuration
- Separate requirements-prod.txt
- Prometheus metrics endpoint (/metrics)

Monitoring:
- Health check endpoints for liveness/readiness
- Prometheus-compatible metrics
- Structured logging
- Memory usage tracking
- Request counting

Security:
- Non-root user in Docker
- Systemd security restrictions
- Nginx security headers
- File permission hardening
- Resource limits

Documentation:
- Comprehensive PRODUCTION_DEPLOYMENT.md
- Scaling strategies
- Performance tuning guide
- Troubleshooting section

Also fixed memory_manager.py GC stats collection error.

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

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

app.py

@@ -1232,6 +1232,50 @@ def liveness_check():
     """Liveness probe - basic check to see if process is alive"""
     return jsonify({'status': 'alive', 'timestamp': time.time()})
 
+@app.route('/metrics', methods=['GET'])
+def prometheus_metrics():
+    """Prometheus-compatible metrics endpoint"""
+    try:
+        # Import prometheus client if available
+        from prometheus_client import generate_latest, Counter, Histogram, Gauge
+        
+        # Define metrics
+        request_count = Counter('talk2me_requests_total', 'Total requests', ['method', 'endpoint'])
+        request_duration = Histogram('talk2me_request_duration_seconds', 'Request duration', ['method', 'endpoint'])
+        active_sessions = Gauge('talk2me_active_sessions', 'Active sessions')
+        memory_usage = Gauge('talk2me_memory_usage_bytes', 'Memory usage', ['type'])
+        
+        # Update metrics
+        if hasattr(app, 'session_manager'):
+            active_sessions.set(len(app.session_manager.sessions))
+        
+        if hasattr(app, 'memory_manager'):
+            stats = app.memory_manager.get_memory_stats()
+            memory_usage.labels(type='process').set(stats.process_memory_mb * 1024 * 1024)
+            memory_usage.labels(type='gpu').set(stats.gpu_memory_mb * 1024 * 1024)
+        
+        return generate_latest()
+    except ImportError:
+        # Prometheus client not installed, return basic metrics
+        metrics = []
+        
+        # Basic metrics in Prometheus format
+        metrics.append(f'# HELP talk2me_up Talk2Me service status')
+        metrics.append(f'# TYPE talk2me_up gauge')
+        metrics.append(f'talk2me_up 1')
+        
+        if hasattr(app, 'request_count'):
+            metrics.append(f'# HELP talk2me_requests_total Total number of requests')
+            metrics.append(f'# TYPE talk2me_requests_total counter')
+            metrics.append(f'talk2me_requests_total {app.request_count}')
+        
+        if hasattr(app, 'session_manager'):
+            metrics.append(f'# HELP talk2me_active_sessions Number of active sessions')
+            metrics.append(f'# TYPE talk2me_active_sessions gauge')
+            metrics.append(f'talk2me_active_sessions {len(app.session_manager.sessions)}')
+        
+        return '\n'.join(metrics), 200, {'Content-Type': 'text/plain; charset=utf-8'}
+
 @app.route('/health/storage', methods=['GET'])
 def storage_health():
     """Check temporary file storage health"""