fix: disable all Docker layer caching in CI

GHA cache was serving stale npm install layers despite cache-bust ARG.
Remove all caching — every build is now fully clean.

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

.github/workflows/build-and-push.yaml

@@ -55,10 +55,7 @@ jobs:
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
-          build-args: |
-            TOOLS_CACHEBUST=${{ github.run_id }}
-          cache-from: type=gha
-          cache-to: type=gha,mode=max
+          no-cache: true
           platforms: linux/amd64
 
   # Build routing proxy image for serverless features