Long circuit rides were matching a segment START early and finding the
segment END hours later on a second pass, producing effort times of
~17000s on a 4.7km segment. The conformance check passed because the
full-circuit track covers all interior points within 50m over 5 hours.
Add a per-sport minimum geometric speed (segment_distance / elapsed_s):
cycling ≥ 1.0 m/s, running ≥ 0.5 m/s, default ≥ 0.2 m/s. When the
check fails, advance past the current start candidate and retry, so a
legitimate later match (e.g. a second lap done at real speed) is still
detected.
- detect.py: truncate started_at to seconds so dedup key survives JSON round-trip
- store.py: dedup by (activity_id, iso-started_at) string key, not object equality
- server.py: extract _scan_segment_for_user helper; trigger background scan
for the creating user's activities when a new segment is saved