Add VERSION file and PR validation workflow

Set release version to 96. Add GitHub Actions workflow that runs
the illustration-validator on pull requests to main.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: adamjohnwright

.github/workflows/validate.yml

@@ -0,0 +1,26 @@
+name: Validate illustrations
+
+on:
+  pull_request:
+    branches: [main]
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Validate icons and EHLDs
+        run: |
+          docker run --rm \
+            -v ${{ github.workspace }}/references.txt:/app/references.txt \
+            -v ${{ github.workspace }}/categories.txt:/app/categories.txt \
+            -v ${{ github.workspace }}/icons:/data/icons \
+            -v ${{ github.workspace }}/ehld:/data/ehld \
+            public.ecr.aws/reactome/illustration-validator:latest \
+            java -jar ./target/illustration-validator-jar-with-dependencies.jar \
+            -r /app/references.txt \
+            -c /app/categories.txt \
+            -e false \
+            -d /data/icons \
+            -s /data/ehld

VERSION

@@ -0,0 +1 @@
+96