CI: test.yml never runs on dev, so no feature PR is tested before merge

[stonematt]

What to build

test.yml runs the suite on dev as well as master, so feature PRs are gated by CI before they land.

Today the workflow triggers only on master:

on:
  push:
    branches: [master]
  pull_request:
    branches: [master]

The branch flow is feature → dev → master. A PR into dev targets dev, so it matches neither trigger, and pushes to dev match neither either. The result is that no feature PR ever runs the test suite — all 198 tests stay idle until the release PR from dev to master.

This surfaced on PR #90, which reported "no checks reported." That looked like a docs-only artifact at the time. It isn't: it is true of every PR into dev, code included. Bugs land on dev untested and are only caught at release, which is the worst moment to find them.

Acceptance criteria

• test.yml triggers on pull_request targeting dev
• test.yml triggers on push to dev
• master coverage is unchanged
• A PR into dev shows the Node 18/20/22 matrix as required checks

Blocked by

None — can start immediately.