Add VirusTotal scans for submitted PDFs

Submit locally crafted PDFs (currently, dark mode is broken and I'm
refactoring the CSS and HTML to fix this). First runs likely will fail
due to how runners work on GitHub Actions.

Signed-off-by: nopeitsnothing <no@anonymousplanet.org>

.github/workflows/vt-scan.yml

@@ -0,0 +1,28 @@
+name: '🦠 VirusTotal Scan'
+
+on:
+    release:
+      types: [published]
+      branches:
+        - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: '📦 Checkout'
+        uses: actions/checkout@v6
+
+      - name: '📦 Set up Go'
+        uses: actions/setup-go@v4
+        with:
+            go-version: '1.26.2'
+      - run: go version
+
+      - name: '🦠 Scan PDF files using VT'
+        uses: crazy-max/ghaction-virustotal@v3
+        with:
+          vt_api_key: ${{ secrets.VT_API_KEY }}
+          files: |
+            ./export/thgtoa.pdf
+            ./export/thgtoa-dark.pdf