fix(upload): parse multipart form fields before loadUploadSessionForChunk to fix req.body undefined

[Git-Shubham14]

Description

Fixes #203

The chunk upload route was failing with a 500 error because req.body was undefined when loadUploadSessionForChunk tried to destructure sessionId and chunkIndex from it.

Root Cause:
The client sends chunk data as multipart/form-data (FormData). Multer only parses req.body when it runs — but loadUploadSessionForChunk was executing before multer, so req.body was always empty at that point.

Fix:
Added a fieldParser using multer().none() as the first middleware in chunkUploadMiddleware. This parses the multipart form fields (sessionId, chunkIndex) into req.body before loadUploadSessionForChunk runs, without consuming the file chunk itself.

Type of Change

• Bug fix

Checklist

• Code follows project style
• Tested locally (blocked by additional pre-existing server bugs — duplicate passwordAttemptLimiter in rateLimiter.js and missing rate-limit-redis package preventing server from starting)
• Updated documentation

Pre-existing Issues Found (not caused by this PR)

• rateLimiter.js — duplicate passwordAttemptLimiter declaration (can be raised as separate issue)
• rate-limit-redis package missing from dependencies (Redis not configured locally)
• validateEnv.js — duplicate export default (already fixed in this branch)

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[Git-Shubham14]

Hii @imanchalsingh, please check the pr and let me know is it successfully works or not