Purge Fly.io proxy cache after docs release

The Fly.io nginx proxy caches docs responses for 24h. After a release,
the new content wasn't visible until the cache expired. Add flyctl install
and cache purge steps to the build workflow, running after ArgoCD deploy.

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

.forgejo/workflows/build-blumeops.yaml

@@ -322,6 +322,19 @@ jobs:
 
           echo "Docs app synced successfully!"
 
+      - name: Install flyctl
+        run: |
+          curl -L https://fly.io/install.sh | sh
+          echo "/root/.fly/bin" >> "$GITHUB_PATH"
+
+      - name: Purge Fly.io proxy cache
+        env:
+          FLY_API_TOKEN: ${{ secrets.FLY_DEPLOY_TOKEN }}
+        run: |
+          echo "Purging nginx cache on Fly.io proxy..."
+          fly ssh console -a blumeops-proxy -C "rm -rf /tmp/cache && nginx -s reload"
+          echo "Cache purged"
+
       - name: Summary
         run: |
           VERSION="${{ steps.version.outputs.version }}"

docs/changelog.d/fix-purge-fly-cache-on-release.bugfix.md

@@ -0,0 +1 @@
+Purge Fly.io proxy cache after docs deploy so new releases are served immediately.