feat(api): Rename importCsv to importUniversalCsv for clarity and documentation

- Updated the function name from importCsv to importUniversalCsv to better reflect its purpose.
- Added documentation comment to clarify the parameters used in the universal CSV import process.

frontend/src/utils/api.js

@@ -489,7 +489,8 @@ export const api = {
     req(module ? `/csv/mappings?module=${encodeURIComponent(module)}` : '/csv/mappings'),
   copyCsvMapping: (mappingId, body = null) =>
     req(`/csv/mappings/${mappingId}/copy`, body ? json(body) : { method: 'POST' }),
-  importCsv: async (file, module, mappingId) => {
+  /** Universal-CSV (Issue #21): file + module + mapping_id aus /csv/mappings */
+  importUniversalCsv: async (file, module, mappingId) => {
     const fd = new FormData()
     fd.append('file', file)
     fd.append('module', module)