merge: add render-diagrams workflow

.gitea/workflows/render-diagrams.yml

@@ -0,0 +1,42 @@
+name: Render PlantUML Diagrams
+
+on:
+  push:
+    branches: ["main", "develop", "release/**"]
+    paths:
+      - "docs/diagrams/**.puml"
+
+jobs:
+  render:
+    name: Render .puml → .png
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          token: ${{ secrets.GITEA_TOKEN }}
+
+      - name: Install Java & Graphviz
+        run: |
+          sudo apt-get update -qq
+          sudo apt-get install -y --no-install-recommends default-jre-headless graphviz
+
+      - name: Download PlantUML jar
+        run: |
+          curl -sSL -o /usr/local/bin/plantuml.jar \
+            https://github.com/plantuml/plantuml/releases/download/v1.2024.6/plantuml-1.2024.6.jar
+
+      - name: Render diagrams
+        run: |
+          java -jar /usr/local/bin/plantuml.jar -tpng -o . docs/diagrams/*.puml
+
+      - name: Commit rendered PNGs
+        run: |
+          git config user.name  "gitea-actions[bot]"
+          git config user.email "gitea-actions[bot]@i3omb.com"
+          git add docs/diagrams/*.png
+          if git diff --cached --quiet; then
+            echo "No diagram changes to commit."
+          else
+            git commit -m "ci: render PlantUML diagrams [skip ci]"
+            git push
+          fi