Publish to harperdb npm package in addition to harper

## Request

Update the release pipeline to publish to the `harperdb` npm package in addition to `harper` and `@harperfast/harper`, for backwards compatibility with users still on the legacy `harperdb` package name.

## Current state

`publish-npm.yaml` publishes to:
- `harper` (public)
- `@harperfast/harper` (scoped)

## Proposed

Add a third publish job for `harperdb`, updating `package.json` name to `harperdb` before packing/publishing (same pattern as the existing `@harperfast/harper` publish job).

## Note

Assess whether `harperdb` publishing is still desirable given the v5.x rebranding, or if users should be migrated to `harper`/`@harperfast/harper`.

🤖 Filed by Claude on behalf of Kris.