Fix and clarify workflow logic, add branch versioning

- `pr.yml` should've been deleted a long time ago. Its functionality
  was already elsewhere, and that's since been folded into `test.yml`.
- I added automatic `release-v*` and `main-v*` versioning.
- Renamed `merge.yml` to `push-release.yml` and `push-main.yml` to
  `pr-create-release.yml` so it's clearer what they're actually
  listening to. I also modified their display names.

.github/workflows/push-release.yml

@@ -0,0 +1,33 @@
+name: Create release when pushing to `release`
+
+on:
+  push:
+    branches: [release]
+  workflow_dispatch:
+
+concurrency: merge-release
+
+jobs:
+  merge:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        ref: main
+    - uses: actions/setup-node@v4
+      with:
+        node-version: 20
+    - run: npm ci
+    - run: npm run build
+    - run: npx pr-release merge --target release --source main --commit --force --clean --changelog ./docs/recent-changes.md --compact --minimize-semver-change
+      env:
+        GITHUB_TOKEN: ${{ secrets.GH_TOKEN }}
+    - run: bash scripts/set-versioned-branch.sh release
+    # The following will publish the release to npm
+    - run: echo "//registry.npmjs.org/:_authToken=$NPM_TOKEN" > ~/.npmrc
+      name: Setup NPM Auth
+      env:
+        NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+    - run: npm publish
+      name: Publish