[Backend] add-loan-events-missing-indexes has an empty down(), leaking four indexes on rollback

[grantfox-oss]

Telegram (ask questions / claim the issue here first): https://t.me/+DOylgFv1jyJlNzM0

Why this matters

migrations/1788000000018_add-loan-events-missing-indexes.js:43 defines down = () => {} (no-op), so rolling this migration back leaves idx_loan_events_borrower, idx_loan_events_event_type, idx_loan_events_loan_id_event_type and idx_loan_events_created_at behind. A re-apply or a later differently-defined index of the same name then collides, and the migration is not truly reversible.

Acceptance criteria

• Implement down() to DROP INDEX IF EXISTS each of the four indexes created in up()
• Confirm migrate:down then migrate:up round-trips cleanly

Files to touch

• backend/migrations/1788000000018_add-loan-events-missing-indexes.js

Out of scope

• Colliding migration timestamp prefixes (already filed)

[Chrisland58]

Hi maintainer I will like to work on this issue

[SharifIbrahimDev]

@SharifIbrahimDev has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this issue

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[khanavi272-spec]

@khanavi272-spec has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @khanavi272-spec to this issue.

[grantfox-oss]

🦊 GrantFox — @SharifIbrahimDev has been assigned to this issue!

Next steps:

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