Enhanced: Comprehensive production debugging and Nginx proxy support

Debugging Tools:
- Added /debug endpoint to verify deployment and test distribution functionality
- Added browser console test function: testDistributionChart()
- Enhanced SocketIO settings with better transport priorities
- Added comprehensive error tracking and status reporting

Nginx Configuration:
- Created NGINX_CONFIG.md with complete proxy setup guide
- Improved WebSocket transport settings and timeouts
- Better ping/pong settings for connection stability

Production Compatibility:
- Optimized SocketIO for proxy environments
- Enhanced fallback mechanisms
- Production-ready logging and error handling

This should resolve proxy-related issues and provide clear diagnostic tools.

app/static/js/simulation.js

@@ -1,3 +1,63 @@
+/**
+ * Production debugging test function
+ * Call from browser console: testDistributionChart()
+ */
+window.testDistributionChart = function() {
+    debugLog('=== DISTRIBUTION CHART DIAGNOSTIC TEST ===');
+    
+    // Test 1: Check if elements exist
+    const canvas = document.getElementById('distributionChart');
+    debugLog('Canvas element found', !!canvas);
+    
+    // Test 2: Check Chart.js availability
+    debugLog('Chart.js available', typeof Chart !== 'undefined');
+    
+    // Test 3: Check chart instance
+    debugLog('Chart instance exists', !!charts.distribution);
+    
+    // Test 4: Check current data
+    debugLog('Current simulation data', {
+        hasId: !!currentSimulation.id,
+        isRunning: currentSimulation.isRunning,
+        distributionData: currentSimulation.data.distribution
+    });
+    
+    // Test 5: Check WebSocket connection
+    debugLog('WebSocket status', {
+        socketExists: !!window.MarkovEconomics.socket,
+        isConnected: window.MarkovEconomics ? window.MarkovEconomics.isConnected : 'unknown'
+    });
+    
+    // Test 6: Manually test API endpoint
+    if (currentSimulation.id) {
+        fetch(`/api/simulation/${currentSimulation.id}/distribution?bins=5`)
+            .then(response => response.json())
+            .then(data => {
+                debugLog('Manual API test result', data);
+            })
+            .catch(error => {
+                debugLog('Manual API test failed', error);
+            });
+    }
+    
+    // Test 7: Try to create test data and update chart
+    if (charts.distribution) {
+        const testLabels = ['$0-100', '$100-200', '$200-300'];
+        const testCounts = [5, 8, 2];
+        
+        try {
+            charts.distribution.data.labels = testLabels;
+            charts.distribution.data.datasets[0].data = testCounts;
+            charts.distribution.update();
+            debugLog('Manual chart update test: SUCCESS');
+        } catch (error) {
+            debugLog('Manual chart update test: FAILED', error);
+        }
+    }
+    
+    debugLog('=== TEST COMPLETE ===');
+};
+
 // Debug flag - can be enabled even in production for troubleshooting
 const DEBUG_DISTRIBUTION = true;