refactor(site): extract CSS to assets/style.css and add deploy badge placeholder

.gitea/workflows/deploy.yml

@@ -51,6 +51,18 @@ jobs:
           ssh-keyscan -H "$DEPLOY_HOST" >> ~/.ssh/known_hosts 2>/dev/null
           chmod 600 ~/.ssh/known_hosts
 
+      - name: Inject deploy info
+        run: |
+          set -euo pipefail
+          SHA_SHORT=$(echo "${GITHUB_SHA}" | cut -c1-7)
+          DEPLOY_TS=$(date -u +"%Y-%m-%d %H:%M UTC")
+          DEPLOY_INFO="${SHA_SHORT} · ${DEPLOY_TS}"
+          # In-place substitute the <!--DEPLOY_INFO--> placeholder in all HTML files.
+          # Pipe `|` is used as the sed delimiter to avoid clashing with `/` in the timestamp.
+          # GNU sed on the Ubuntu runner accepts `-i` without a backup arg.
+          find site -name "*.html" -exec sed -i "s|<!--DEPLOY_INFO-->|${DEPLOY_INFO}|g" {} +
+          echo "Injected deploy info: ${DEPLOY_INFO}"
+
       - name: Rsync site/ to IONOS DocumentRoot
         run: |
           set -euo pipefail