actions: experimental thumbs artifact

Also renames an unrelated file... Groan...

.github/workflows/archive_thumbnails_artifact.yml

@@ -0,0 +1,46 @@
+name: Archive Thumbnails Artifact
+
+on:
+  push:
+    branches: [ "release" "staging" "preview" ]
+
+  workflow_dispatch: null
+
+jobs:
+  prepare_media:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Install ImageMagick
+        uses: awalsh128/cache-apt-pkgs-action@latest
+        with:
+          packages: imagemagick
+          version: 1.0
+
+      - name: Checkout corresponding canonical data repo
+        uses: actions/checkout@v4
+        with:
+          repository: hsmusic/hsmusic-data
+          ref: ${{ github.ref_name }}
+          path: data
+
+      - name: Checkout media repo
+        uses: actions/checkout@v4
+        with:
+          repository: hsmusic/hsmusic-media
+          ref: ${{ github.ref }}
+          path: media
+
+      - name: Generate thumbnails
+        run: |
+          node code/src/upd8.js \
+            --show-step-summary \
+            --data-path data \
+            --media-path media \
+            --thumbs-only
+
+      - name: Archive thumbnails artifact
+        uses: actions/upload-artifact@v3
+        with:
+          name: media
+          path: media