f376b24106
resolveShards rewrites detail_url to absolute paths (e.g. /data/brut/_merged/activities/{id}.json)
when fetching from a user shard. loadActivity and loadTimeseries only checked for http:// prefixes
and treated /data/... paths as relative, producing double /data//data/... in the fetch URL → 404.
Fix: treat URLs starting with / as already absolute, same as http:// URLs.