refactor(backend): standardize error responses, logging, pagination

- errorResponse(res, error, status, publicMessage) in routeHelpers,
  wired into 125 catch blocks across 10 route files; wire format
  ({ error: <string> }) unchanged byte-for-byte
- Replace remaining console.* with logger across src (178 sites);
  3 intentional console sites kept (install boot, unbound .catch ref)
- Adopt getPagination in 6 routes where semantics match exactly

backend/src/utils/dateFormatter.js

@@ -1,4 +1,5 @@
 const { db } = require('../database/db');
+const logger = require('./logger');
 
 // Default date format settings
 const DEFAULT_FORMAT = {
@@ -19,7 +20,7 @@ async function formatDate(date, language = 'en') {
         try {
           dateConfig = JSON.parse(setting.setting_value);
         } catch (e) {
-          console.warn('Failed to parse date format setting:', e.message);
+          logger.warn('Failed to parse date format setting:', e.message);
           dateConfig = DEFAULT_FORMAT;
         }
       } else {
@@ -46,7 +47,7 @@ async function formatDate(date, language = 'en') {
     
     // Check if date is valid
     if (isNaN(dateObj.getTime())) {
-      console.error('Invalid date provided to formatDate:', date);
+      logger.error('Invalid date provided to formatDate:', date);
       throw new Error('Invalid date');
     }
     
@@ -91,7 +92,7 @@ async function formatDate(date, language = 'en') {
       });
     }
   } catch (error) {
-    console.error('Error formatting date:', error);
+    logger.error('Error formatting date:', error);
     // Fallback to basic formatting
     return date instanceof Date ? date.toLocaleDateString() : new Date(date).toLocaleDateString();
   }

backend/src/utils/dbCompat.js

@@ -5,6 +5,7 @@
 
 // Note: Requiring db here creates circular dependency
 // db should be passed as parameter or required where needed
+const logger = require('./logger');
 
 /**
  * Get database client type
@@ -91,7 +92,7 @@ async function getDatabaseSize(db, dbName) {
       const stats = await fs.stat(dbPath);
       return stats.size;
     } catch (error) {
-      console.error('Error getting SQLite database size:', error);
+      logger.error('Error getting SQLite database size:', error);
       return 0;
     }
   }

backend/src/utils/fileSecurityUtils.js

@@ -1,5 +1,6 @@
 const path = require('path');
 const fs = require('fs').promises;
+const logger = require('./logger');
 
 /**
  * Secure file security utilities to prevent path traversal and validate file types
@@ -174,7 +175,7 @@ async function validateFileContent(filePath, expectedMimeType) {
       return true;
     });
   } catch (error) {
-    console.error('Error validating file content:', error);
+    logger.error('Error validating file content:', error);
     return false;
   }
 }
@@ -239,7 +240,7 @@ function createFileUploadValidator(options = {}) {
             try {
               await fs.unlink(file.path);
             } catch (err) {
-              console.error('Error removing invalid file:', err);
+              logger.error('Error removing invalid file:', err);
             }
             return res.status(400).json({ 
               error: `File content does not match declared type: ${file.originalname}` 
@@ -250,7 +251,7 @@ function createFileUploadValidator(options = {}) {
       
       next();
     } catch (error) {
-      console.error('File validation error:', error);
+      logger.error('File validation error:', error);
       res.status(500).json({ error: 'File validation failed' });
     }
   };

backend/src/utils/routeHelpers.js

@@ -5,6 +5,7 @@
 
 const { validationResult } = require('express-validator');
 const { ValidationError } = require('./errors');
+const logger = require('./logger');
 
 /**
  * Wraps an async route handler to catch errors and pass them to the error handler.
@@ -69,25 +70,26 @@ const successResponse = (res, data, statusCode = 200, message = null) => {
 };
 
 /**
- * Sends a standardized error response.
- * Note: Prefer throwing custom errors and letting the error handler format the response.
+ * Logs an error and sends a standardized error response of shape `{ error: <string> }`.
  *
  * @param {Response} res - Express response object
- * @param {string} message - Error message
+ * @param {Error|*} error - The caught error (logged, never sent to the client)
  * @param {number} [statusCode=500] - HTTP status code
- * @param {string} [code] - Optional error code
- * @param {*} [details] - Optional additional error details
+ * @param {string} [publicMessage] - Message sent to the client; falls back to the error's message
  *
  * @example
- * errorResponse(res, 'Invalid input', 400, 'VALIDATION_ERROR', { field: 'email' });
+ * } catch (error) {
+ *   errorResponse(res, error, 500, 'Failed to fetch events');
+ * }
  */
-const errorResponse = (res, message, statusCode = 500, code = null, details = null) => {
-  const response = {
-    error: message,
-    ...(code && { code }),
-    ...(details && { details })
-  };
-  res.status(statusCode).json(response);
+const errorResponse = (res, error, statusCode = 500, publicMessage) => {
+  const message = publicMessage || (error instanceof Error ? error.message : String(error));
+  const route = res.req ? `${res.req.method} ${res.req.originalUrl}` : null;
+  logger.error(route ? `${route} - ${message}` : message, {
+    error: error instanceof Error ? error.message : error,
+    stack: error instanceof Error ? error.stack : undefined
+  });
+  res.status(statusCode).json({ error: message });
 };
 
 /**