Fix CI: use sharp prebuilt binaries for faster builds

Instead of installing libvips-dev and build-essential to compile
sharp from source, use SHARP_IGNORE_GLOBAL_LIBVIPS=1 to force
sharp to use its bundled prebuilt binaries.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: Nik Samokhvalov

.gitlab-ci.yml

@@ -27,8 +27,10 @@ validate_feeds:
   stage: validate
   image: oven/bun:1.3-debian
   before_script:
-    # Install xmllint for XML validation and libvips for sharp (image processing)
-    - apt-get update && apt-get install -y libxml2-utils jq libvips-dev build-essential
+    # Install xmllint for XML validation
+    - apt-get update && apt-get install -y libxml2-utils jq
+    # Use sharp's prebuilt binaries (faster than compiling from source)
+    - export SHARP_IGNORE_GLOBAL_LIBVIPS=1
     - bun install --frozen-lockfile
   script:
     - bash .ci/validate-feeds.sh