Fix CI: add libvips-dev for sharp module

The sharp image processing module requires libvips to be installed.
Adding libvips-dev to the validate_feeds job to resolve the build error.

Author: claude

.gitlab-ci.yml

@@ -27,8 +27,8 @@ validate_feeds:
   stage: validate
   image: oven/bun:1.3-debian
   before_script:
-    # Install xmllint for XML validation
-    - apt-get update && apt-get install -y libxml2-utils jq
+    # Install xmllint for XML validation and libvips for sharp (image processing)
+    - apt-get update && apt-get install -y libxml2-utils jq libvips-dev
     - bun install --frozen-lockfile
   script:
     - bash .ci/validate-feeds.sh