fix(coupon): properly update usage_count on promo_codes table in recordCouponUsage

[Pratyush-Panda-2006]

Description

Fixes promo code usage tracking in \�ackend/services/couponService.js. Previously,
ecordCouponUsage\ exclusively updated the \coupons\ table, meaning coupons redeemed from the fallback \promo_codes\ table never had their \usage_count\ incremented, resulting in unlimited redemptions.

Related Issue

Closes #1692

Clean Architecture & Changes

• Supported \isPromoTable\ parameter and added automatic fallback to \promo_codes\ table when \coupons\ update does not match any rows.
• Incremented \usage_count\ properly on \promo_codes.
• Added unit tests in \�ackend/tests/promoCodeUsage.test.js\ validating \promo_codes\ usage updates.

Verification

• Run
  px jest tests/promoCodeUsage.test.js\ (All unit tests passing cleanly).

[hydra-maintainer]

🔍 Quality Gate Report

✅ All quality gates passed!

Status	Check	Details
✅	Linked Issue	PR description references a closing issue ✅

[vercel]

@Pratyush-Panda-2006 is attempting to deploy a commit to the Bhuvansh's projects Team on Vercel.

A member of the Team first needs to authorize it.

[hydra-maintainer]

🤖 AI Code Review

🔴 Score: 50/100 | comment

AI review unavailable at this time.

---

Automated AI review — a human maintainer will also review.

[hydra-maintainer]

💡 Suggested reviewers based on relevant file history: @Aditya8369, @MOHITKOURAV01