Add API logging functionality and enhance scheduler service

Introduced ApiLog model and integrated logging for scheduled tasks in the SchedulerService. Updated server.js to include request logging middleware and new API log routes. Enhanced frontend navigation by adding a link to system logs for admin users. Adjusted session check interval in App.vue for improved performance. This update improves monitoring and debugging capabilities across the application.

backend/middleware/requestLoggingMiddleware.js

@@ -0,0 +1,83 @@
+import ApiLog from '../models/ApiLog.js';
+
+/**
+ * Middleware to log all API requests and responses
+ * Should be added early in the middleware chain, but after authentication
+ */
+export const requestLoggingMiddleware = async (req, res, next) => {
+  const startTime = Date.now();
+  const originalSend = res.send;
+  
+  // Get request body (but limit size for sensitive data)
+  let requestBody = null;
+  if (req.body && Object.keys(req.body).length > 0) {
+    const bodyStr = JSON.stringify(req.body);
+    // Truncate very long bodies
+    requestBody = bodyStr.length > 10000 ? bodyStr.substring(0, 10000) + '... (truncated)' : bodyStr;
+  }
+  
+  // Capture response
+  let responseBody = null;
+  res.send = function(data) {
+    // Try to parse response as JSON
+    try {
+      const parsed = JSON.parse(data);
+      const responseStr = JSON.stringify(parsed);
+      // Truncate very long responses
+      responseBody = responseStr.length > 10000 ? responseStr.substring(0, 10000) + '... (truncated)' : responseStr;
+    } catch (e) {
+      // Not JSON, just use raw data (truncated)
+      responseBody = typeof data === 'string' ? data.substring(0, 1000) : String(data).substring(0, 1000);
+    }
+    
+    // Restore original send
+    res.send = originalSend;
+    return res.send.apply(res, arguments);
+  };
+  
+  // Log after response is sent
+  res.on('finish', async () => {
+    const executionTime = Date.now() - startTime;
+    const ipAddress = req.ip || req.connection.remoteAddress || req.headers['x-forwarded-for'];
+    const path = req.path || req.url;
+    
+    // Skip logging for non-data endpoints (Status-Checks, Health-Checks, etc.)
+    // Nur Daten-Abrufe von API-Endpunkten werden geloggt
+    const skipPaths = [
+      '/status',
+      '/session/status',
+      '/health',
+      '/',
+      '/scheduler-status'
+    ];
+    
+    if (skipPaths.some(skipPath => path.includes(skipPath))) {
+      return;
+    }
+    
+    // Get user ID if available (wird von authMiddleware gesetzt)
+    const userId = req.user?.id || null;
+    
+    try {
+      await ApiLog.create({
+        userId,
+        method: req.method,
+        path: path,
+        statusCode: res.statusCode,
+        requestBody,
+        responseBody,
+        executionTime,
+        errorMessage: res.statusCode >= 400 ? `HTTP ${res.statusCode}` : null,
+        ipAddress,
+        userAgent: req.headers['user-agent'],
+        logType: 'api_request'
+      });
+    } catch (error) {
+      // Don't let logging errors break the request
+      console.error('Error logging API request:', error);
+    }
+  });
+  
+  next();
+};
+