The EC volumes, EC shards, and collection details pages each rendered a
repair (wrench) button for incomplete EC volumes. Its handler POSTed to a
/repair endpoint that the admin server never registers, so every click
returned "404 page not found" (the collection details page only had a
placeholder handler).
Remove the buttons and their JavaScript handlers, and regenerate the
templ output. Manual EC shard recovery remains available from weed shell
via ec.rebuild.