Add no-cache headers for WordPress plugin downloads

Prevents Cloudflare from caching zip file responses.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

frontend/Dockerfile

@@ -41,6 +41,13 @@ RUN echo 'server { \
         add_header Cache-Control "public, immutable"; \
     } \
     \
+    # WordPress plugin downloads - no cache for zip files \
+    location /wordpress/ { \
+        add_header Cache-Control "no-cache, must-revalidate"; \
+        types { application/zip zip; } \
+        default_type application/octet-stream; \
+    } \
+    \
     # SPA fallback - serve index.html for all routes \
     location / { \
         try_files $uri $uri/ /index.html; \