fix(ci): use ghcr.io for Trivy vulnerability DB download (#363)

Trivy defaults to mirror.gcr.io for DB download, which is blocked
by harden-runner egress policy. Use ghcr.io/aquasecurity/trivy-db:2
instead, which is already in allowed-endpoints.

🖥️ IDE: [Cursor](https://cursor.sh)
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Model-Raw: claude-opus-4-6-20250514

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: nullvariant

.github/workflows/publish.yml

@@ -80,7 +80,8 @@ jobs:
           chmod +x trivy
           ./trivy fs extensions/git-id-switcher \
             --severity CRITICAL,HIGH \
-            --exit-code 1
+            --exit-code 1 \
+            --db-repository ghcr.io/aquasecurity/trivy-db:2
           rm -f trivy trivy.tar.gz
 
       # Supply Chain Security: Cosign keyless signing for VSIX