refactor: remove unused mongoose dependency

[vinamra1102]

What this fixes

Closes #223

Description

mongoose (^9.6.2) was listed in package.json dependencies
but is never imported or used as a module anywhere in the
codebase. The app uses Prisma exclusively for all database
operations.

mongoose only appears as a string inside a regex pattern in
a repository analyzer utility for detecting DB libraries in
other repos — not as an actual import.

Change made

• Removed mongoose from package.json dependencies
• Updated pnpm-lock.yaml accordingly

Verified

Searched entire codebase — no actual imports of mongoose found:

• No require('mongoose')
• No import mongoose
• No from 'mongoose'

Impact

• Reduces bundle size
• Removes unnecessary CVE attack surface
• Keeps dependencies accurate

Type

• Refactor

Suggested Labels

level-1 refactor backend

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