The nixpkgs ntfy-sh package is pinned at 2.15.0, creating a version
skew with the Dockerfile (v2.17.0). Replace the pkgs.ntfy-sh reference
with a custom derivation using fetchgit, buildNpmPackage, and
buildGoModule targeting the forge mirror. Update container-version-check
to extract versions from local nix files via regex before falling back
to the Dagger nix-version function.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>