feat: add append-only course/user data import and expand user profile

Support uploading structured JSON to create courses, classes, and students without wiping existing data, and merge user name fields while adding gender and registration details from source sheets.

components/dataImport/dataImportController.js

@@ -0,0 +1,28 @@
+// /components/dataImport/dataImportController.js
+'use strict';
+
+const catchAsync = require('../../utils/catchAsync');
+const dataImportService = require('./dataImportService');
+const AppError = require('../../utils/AppError');
+const { successResponse } = require('../../utils/apiResponse');
+
+exports.importJson = catchAsync(async (req, res) => {
+  let payload = req.body;
+
+  if (req.file?.buffer) {
+    try {
+      payload = JSON.parse(req.file.buffer.toString('utf8'));
+    } catch {
+      throw new AppError('VALIDATION_FAILED', null, 'Uploaded file is not valid JSON');
+    }
+  }
+
+  // Allow { data: { courses: [...] } } wrappers
+  if (payload?.data?.courses) payload = payload.data;
+  if (!payload?.courses && payload?.version && payload?.courses == null) {
+    throw new AppError('VALIDATION_FAILED', null, 'Invalid import payload');
+  }
+
+  const result = await dataImportService.importData(payload);
+  return successResponse(res, 200, 'Data imported successfully', result);
+});