ci(render): add -failfast2 to plantuml invocation

Without it, a render error writes the error text into the SVG and
exits zero, so CI goes green while committing a broken diagram.
Caught this after overview.svg was silently replaced by a one-line
error file.

Author: jknoxdev

.github/workflows/render-diagrams.yml

@@ -39,10 +39,10 @@ jobs:
             "https://github.com/plantuml/plantuml/releases/download/v${PLANTUML_VERSION}/plantuml-${PLANTUML_VERSION}.jar"
           java -jar plantuml.jar -version
 
-      - name: Render SVG
+      - name: Render diagrams
         run: |
           find . -name '*.puml' -not -path './.git/*' -print0 \
-            | xargs -0 -r java -jar plantuml.jar -tsvg -tpng -nometadata
+            | xargs -0 -r java -jar plantuml.jar -tsvg -tpng -nometadata -failfast2
 
       - name: Commit rendered diagrams
         uses: stefanzweifel/git-auto-commit-action@v5