* Fix all golangci-lint issues across the codebase
Resolve 77 lint issues reported by golangci-lint with gocritic, gocognit,
gocyclo, maintidx, dupl, mnd, unparam, ireturn, goconst, and errcheck
enabled. Net reduction of ~175 lines through shared helpers and
deduplication.
* Suppress staticcheck SA1019 for intentional deprecated field usage
The Storage.Path field is deprecated but still read for backwards
compatibility with existing configs that haven't migrated to the URL field.
All handler metadata and proxy requests were using http.DefaultClient directly,
bypassing any timeout or transport configuration. Added an HTTPClient field to
the Proxy struct with a 30-second default timeout, and updated every handler
to use it for upstream HTTP requests.
Adds proxy support for Docker/OCI container registries, Debian/APT
repositories, and RPM/Yum repositories. Includes a new enrichment API
for package metadata, vulnerability scanning, and outdated detection.
Updates the dashboard with Tailwind CSS, dark mode support, and a
security overview section showing vulnerability counts.
