Fix/db unique loan events

[mijinummi]

📝 Description

Overview

This PR adds a unique constraint to the loan_events table and updates the event indexer to prevent duplicate entries.

Key Features

• Unique constraint on (transaction_hash, event_index)
• Updated indexer insert logic with ON CONFLICT DO NOTHING
• Ensures idempotent re‑indexing
• Prevents double‑counted repayments and inflated event history

---

Closes #439

[ogazboiz]

The contracts CI is failing on the rustfmt format check. This isn't a logic issue, just formatting.

Run this in the contracts directory and push:

cd contracts
cargo fmt

Then commit and push the formatting changes. The CI should pass after that.

[ogazboiz]

Backend CI is failing with a Jest environment error:

ReferenceError: You are trying to `import` a file after the Jest environment has been torn down.

This usually means a test file has async operations that outlive the test suite — either missing await on async teardown, or an import that fires a side effect (like a Redis/DB connection) after the test runner has already cleaned up.

To fix: check if any test files in your PR have async operations in top-level scope without proper beforeAll/afterAll cleanup. Also make sure any mocks for Redis or DB are set up before the app module is imported.

Contracts CI is also failing on cargo fmt. Run cargo fmt in the contracts/ directory and push the formatting changes.

[ogazboiz]

Two failures to fix:

Contracts CI: Failing under 30s, which is a cargo fmt issue.

cd contracts
cargo fmt

Backend CI: eventIndexer.test.ts failure. Rebase on main to pick up the recent test fix:

git fetch upstream
git rebase upstream/main

Commit, format, and push when done.

[ogazboiz]

The codebase issues on main have been resolved and all CI checks are passing now. Please rebase your branch to pull in the latest changes before continuing. Thanks for your patience.

[ogazboiz]

Nearly identical to #519. Consolidate with #519 or close one. Same migration naming issue, same code quality issues. Fix ESM import paths and migration numbers.

[ogazboiz]

heads up, a few important changes just landed on main that affect your PR:

1. axios pinned to 1.13.5 - there's an active supply chain attack on axios 1.14.1 (pulls in confirmed malware). we added overrides in all package.json files to block it.

2. CI now runs a supply chain audit before backend/frontend jobs. if your lockfile has a compromised package, CI will fail with a clear error.

3. backend test fixes - loanEndpoints tests now use valid Stellar addresses and base64 strings. if your PR was failing backend CI but you didn't touch backend code, this should fix it after rebase.

please rebase on latest main:

git fetch upstream
git rebase upstream/main
git push --force-with-lease