fix(database): move audit_logs DDL into the numbered migration chain

[nello27]

Summary

• database/audit_logs.sql lived as a standalone file, outside database/migrations, and was missing from database/schema.sql — breaking the invariant that applying all migrations in order must reproduce schema.sql exactly.
• Adds 2026071701_add_audit_logs.up.sql / .down.sql following the repo's migration conventions (BEGIN/COMMIT, IF NOT EXISTS guards).
• Adds the audit_logs table to database/schema.sql.
• Updates database/migrations/README.md listing table.
• Removes the standalone database/audit_logs.sql.

Closes #333

Test plan

• Applied the up migration on a fresh Postgres (Docker) DB seeded with the prior schema — table, indexes, and FK to users(id) created correctly.
• Re-ran the up migration — confirmed idempotent (IF NOT EXISTS skips).
• Ran the down migration — confirmed clean rollback (table dropped).
• Re-applied up, then compared pg_dump --schema-only of the migrated DB against a DB loaded directly from schema.sql — identical (only the pg_dump \restrict tokens differ, which are random per-run).

[Xhristin3]

Good catch and solid fix, @nello27 — keeping the audit_logs DDL inside the numbered migration chain ensures the schema evolves predictably and deployments stay repeatable. CI is green. Merging! 🚀

[Xhristin3]

Hey @nello27, the migration chain fix is exactly the right approach and CI is green ✅.

The branch has picked up conflicts with main (mainly package-lock.json) from other PRs that landed recently. Quick rebase to clear it:

git fetch origin
git rebase origin/main
# resolve any conflicts, then
git push --force-with-lease

Ready to merge once the branch is updated!

[Xhristin3]

@nello27 resolve conflicts.

[nello27]

Investigated the failing CI / quality check — it's caused by a pre-existing issue on main, unrelated to this PR:

src/streams/streams.service.spec.ts:210:15 - error TS2554: Expected 2 arguments, but got 1.
service = new StreamsService(mockRepo);
An argument for 'webhooksService' was not provided.

StreamsService's constructor now requires a webhooksService argument (likely introduced alongside the recent webhooks module), but streams.service.spec.ts:210 wasn't updated to pass it. This PR only touches database/audit_logs.sql, database/migrations/, and database/schema.sql — no changes to streams.service.ts or its tests.