Handle repo label rename/delete

[MkDev11]

Summary

Handle repository-level label rename/delete webhooks so scoring-visible label state stays aligned with GitHub.

Root cause: label webhook events were skipped as repo-level CRUD, but miner responses derive current PR/issue labels from label_events through pr_labels_by_actor and issue_labels_by_actor. When a repo label was deleted or renamed, the mirror had no repo-wide transition to remove or rename the current per-target label rows.

This PR:

• routes repo-level label events into LabelHandler
• records unlabeled tombstones for currently applied labels when a repo label is deleted
• records an old-name unlabeled plus new-name labeled transition when a repo label is renamed
• preserves the original label actor on renamed labels so actor attribution remains stable
• keeps parent pull_requests.labels and issues.labels arrays in sync

Out of scope: a full repo_labels catalog for color/description/default-label metadata.

Related Issues

Addresses the stale scoring-label state from #101.

Type of Change

• Bug fix
• New feature
• Refactor
• Documentation
• Other (describe below)

Testing

• npm run format:check
• npm run lint
• npm run build
• git diff --check

No automated test suite is configured in packages/das/package.json.

Checklist

• I have read the Contributing Guide
• Code builds without errors
• New and existing tests pass (if applicable)
• Documentation updated (if applicable)
• No unnecessary dependencies added

[MkDev11]

@anderdc can you please review the pr?

[anderdc]

The two new repo-label handlers drop to raw manager.query SQL, but the rest of this file uses the TypeORM repository API (handle(), label.handler.ts:42-74). Please match that style. The behavior and the append-only transition design are correct as-is — this is consistency only, no logic change.

• removeRepoLabel / renameRepoLabel: replace dataSource.transaction(manager.query(...)). Find the currently-labeled targets with a SelectQueryBuilder using .distinctOn(["repo_full_name","target_number","target_type","label_name"]) ordered by timestamp DESC, filtered to action = 'labeled'.
• Insert the transition rows via labelEventRepo.createQueryBuilder().insert().values([...]).orIgnore() instead of the INSERT ... SELECT ... ON CONFLICT.
• Parent arrays: prRepo/issueRepo .createQueryBuilder().update().set({ labels: () => "array_remove(labels, :name)" }).where(":name = ANY(labels)") — keep only the array_remove / array_replace / = ANY fragments raw, since no ORM abstracts Postgres array operators.

This also lets you drop the raw-query eslint-disable and keeps the handler reading like handle().