Add docker-compose integration test harness

[codefather2026]

Summary

Added a docker-compose-based integration test harness for Wraith that runs against a real Postgres instance, seeds representative fixtures, and exercises live API endpoints through Vitest. Also wired the suite into CI so it runs on every pull request.

Related issue

Type of change

• Bug fix
• New feature
• Refactor
• Docs
• Tests
• CI / tooling

Checklist

• I have read CONTRIBUTING.md
• npx tsc --noEmit passes
• npm run build passes
• I added / updated tests where relevant
• I updated docs where relevant

[Miracle656]

Thanks for this. A few things to resolve before it can land:

1. The Integration tests job is failing — Cannot find module '@rolldown/binding-linux-x64-gnu' (the npm optional-deps bug, npm/cli#4828). The committed package-lock.json doesn't include the Linux native binding Vitest needs in CI. Regenerating the lockfile so the platform-optional deps are captured (or pinning the binding) should fix it.

2. Overlap with the existing harness. main already has a docker-compose integration setup (from #65). Please clarify what this adds on top of it — if it's an improvement, ideally extend the existing harness rather than adding a parallel vitest.integration.config.ts path; if it supersedes #65's, say so explicitly.

3. Unrelated change: src/__tests__/opa.test.ts and the src/index.ts edit don't look related to an integration harness — if they belong to a different concern, please split them out.

Once the integration job is green and the relationship to the existing harness is clear, I'll re-review. Thanks!

[codefather2026]

Merge conflict resolved

[Miracle656]

A few things to sort before this can land:

1. Regression: the SKIP_INDEXER early-return replaces the startPartitionRetentionJob() call — so in normal mode the partition retention scheduler no longer starts. Please keep that running (gate only the indexer behind SKIP_INDEXER, not the retention job).
2. Unrelated churn: the lockfile bumps vitest 3.2.4 → 4.1.7 (a major) and shuffles other deps. Please drop that from this PR.
3. The title says "docker-compose integration test harness" but the diff is only src/index.ts + lockfile — no compose file or tests. Could you add the harness itself, or retitle to match the actual change (the SKIP_INDEXER API-only mode)?

The SKIP_INDEXER flag itself is a reasonable addition once those are addressed.