feat: error and logging middleware

[indrasuthar07]

Description

Implemented a centralized logging and error handling system for the backend.

Key Updates

• Integrated Winston for structured logging (multi-level + file & console outputs)

• Added request logger middleware for HTTP method, URL, status, and response time

• Enhanced error handler with custom AppError class and detailed Mongoose/JWT error handling

• Replaced all console.log statements with the new logger

• separate log files created when finds an error

       error.log - errors only 
       combined.log - all logs 
       exceptions.log - unhandled exceptions 
       rejections.log - unhandled promise rejections
  

• Updated .gitignore to exclude log files

Give a brief description of the pull request.

Semver Changes

• Patch (bug fix, no new features)
• Minor (new features, no breaking changes)
• Major (breaking changes)

Issues

closes #14

List any issues that this pull request closes.

Checklist

• I have read the Contributing Guidelines.

[04shubham7]

Looks Fine