fix: show local-repo files in the cached-objects UI

Local repos store uploaded files in the local_files table, while
remote/proxy repos cache into the artifacts table. The shared "Cached
Objects" page always queried the artifacts table via
/api/v2/remotes/{name}/objects, so local packages (e.g. an uploaded RPM)
were servable but listed as "0 objects" in the UI.

- add ListLocalArtifacts, joining local_files with blobs and returning
  models.Artifact-shaped rows (size from the blob; counters zero and
  timestamps derived from created_at, since local files track no access)
- add LocalRoutes to the objects handler: listLocal reads local_files,
  evictLocal deletes via DeleteLocalFile; extract shared page parsing
  into pageBounds
- mount /api/v2/locals/{name}/objects (GET + DELETE) in the server
- add listLocalObjects/evictLocalObject to the UI client and route the
  Objects page to them when viewing a local repo
- cover the listing and eviction paths with a dockerised test

internal/server/server.go

@@ -121,6 +121,12 @@ func (s *Server) routes() chi.Router {
 			r.Delete("/*", objHandler.Routes().ServeHTTP)
 		})
 
+		r.Route("/locals/{name}/objects", func(r chi.Router) {
+			objHandler := v2.NewObjectsHandler(s.db)
+			r.Get("/", objHandler.LocalRoutes().ServeHTTP)
+			r.Delete("/*", objHandler.LocalRoutes().ServeHTTP)
+		})
+
 		r.Route("/remotes/{name}/files", func(r chi.Router) {
 			r.Put("/*", s.localHandler.Routes().ServeHTTP)
 			r.Get("/*", s.localHandler.Routes().ServeHTTP)