detectPlugins(fs: IFileSystem,dir: string): Promise<ReadonlySet<string>>
Detects the @setu-ts packages a project depends on.
Reads deno.json (its imports map) and, when that is absent or carries no
scoped entries, package.json (dependencies + devDependencies).
Detection never boots or imports the target project.
A missing or malformed manifest yields an empty set rather than a throw, so running the CLI outside a project is a plain "plugin not installed" gate rather than a crash.