fix: ensure destination dirs exist before docs-sync rsync

The docs/3.1.0/ directory doesn't exist yet in wheels.dev, causing
rsync to fail with "No such file or directory". Add mkdir -p before
rsync to handle first-time sync for new versions.

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

Author: bpamiri

.github/workflows/docs-sync.yml

@@ -26,6 +26,11 @@ jobs:
 
       - name: Sync docs into wheels.dev
         run: |
+          # Ensure destination directories exist (first sync for a new version)
+          mkdir -p wheels-dev/docs/3.1.0/guides
+          mkdir -p wheels-dev/public/images
+          mkdir -p wheels-dev/public/json
+
           # Guides: mirror with delete
           rsync -av --del wheels/docs/src/ wheels-dev/docs/3.1.0/guides/