fix: generate CSV filename from company name instead of using multer callback

Fixed CSV file upload to properly generate filename based on company name. The previous implementation tried to read `req.body.companyName` in multer's filename callback, but the body is not yet parsed at that point, causing files to be named "unknown.csv".

## Solution
1. Use temporary filename during upload (timestamp + random)
2. After validation and parsing, rename file to proper company name format
3. Delete old file if it exists before renaming
4. Store final filename in database configuration

## Changes
- Multer filename callback now generates temporary filename
- Added file renaming logic after successful validation
- Updated database records to use final filename instead of temp name
- Added logging for file operations

## Impact
- New CSV uploads will have correct filenames (e.g., "ssc-consolidation.csv")
- No more "unknown.csv" files
- Existing "unknown.csv" needs to be manually deleted via dashboard

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/backend/src/application/controllers/admin/csv-rates.controller.ts

@@ -70,14 +70,12 @@ export class CsvRatesAdminController {
       storage: diskStorage({
         destination: './apps/backend/src/infrastructure/storage/csv-storage/rates',
         filename: (req, file, cb) => {
-          // Generate filename: company-name.csv
-          const companyName = req.body.companyName || 'unknown';
-          const sanitized = companyName
-            .toLowerCase()
-            .replace(/\s+/g, '-')
-            .replace(/[^a-z0-9-]/g, '');
-          const filename = `${sanitized}.csv`;
-          cb(null, filename);
+          // Use timestamp + random string to avoid conflicts
+          // We'll rename it later once we have the company name from req.body
+          const timestamp = Date.now();
+          const randomStr = Math.random().toString(36).substring(7);
+          const tempFilename = `temp-${timestamp}-${randomStr}.csv`;
+          cb(null, tempFilename);
         },
       }),
       fileFilter: (req, file, cb) => {
@@ -147,9 +145,16 @@ export class CsvRatesAdminController {
     }
 
     try {
+      // Generate final filename based on company name
+      const sanitizedCompanyName = dto.companyName
+        .toLowerCase()
+        .replace(/\s+/g, '-')
+        .replace(/[^a-z0-9-]/g, '');
+      const finalFilename = `${sanitizedCompanyName}.csv`;
+
       // Auto-convert CSV if needed (FOB FRET → Standard format)
       const conversionResult = await this.csvConverter.autoConvert(file.path, dto.companyName);
-      const filePathToValidate = conversionResult.convertedPath;
+      let filePathToValidate = conversionResult.convertedPath;
 
       if (conversionResult.wasConverted) {
         this.logger.log(
@@ -177,13 +182,28 @@ export class CsvRatesAdminController {
 
       this.logger.log(`Successfully parsed ${ratesCount} rates from ${file.filename}`);
 
+      // Rename file to final name (company-name.csv)
+      const fs = require('fs');
+      const path = require('path');
+      const finalPath = path.join(path.dirname(filePathToValidate), finalFilename);
+
+      // Delete old file if exists
+      if (fs.existsSync(finalPath)) {
+        fs.unlinkSync(finalPath);
+        this.logger.log(`Deleted old file: ${finalFilename}`);
+      }
+
+      // Rename temp file to final name
+      fs.renameSync(filePathToValidate, finalPath);
+      this.logger.log(`Renamed ${file.filename} to ${finalFilename}`);
+
       // Check if config exists for this company
       const existingConfig = await this.csvConfigRepository.findByCompanyName(dto.companyName);
 
       if (existingConfig) {
         // Update existing configuration
         await this.csvConfigRepository.update(existingConfig.id, {
-          csvFilePath: file.filename,
+          csvFilePath: finalFilename,
           uploadedAt: new Date(),
           uploadedBy: user.id,
           rowCount: ratesCount,
@@ -204,7 +224,7 @@ export class CsvRatesAdminController {
         // Create new configuration
         await this.csvConfigRepository.create({
           companyName: dto.companyName,
-          csvFilePath: file.filename,
+          csvFilePath: finalFilename,
           type: 'CSV_ONLY',
           hasApi: false,
           apiConnector: null,
@@ -226,7 +246,7 @@ export class CsvRatesAdminController {
       return {
         success: true,
         ratesCount,
-        csvFilePath: file.filename,
+        csvFilePath: finalFilename,
         companyName: dto.companyName,
         uploadedAt: new Date(),
       };