Replace noisy phone-GPS <ele> in every committed track.gpx with swisstopo swissALTI3D heights at each exact lat/lon (coordinates unchanged; phone altitude was off by up to ~430m).
- scripts/fix-altitudes.ts: batched swisstopo profile.json lookup, WGS84->LV95, disk-cached, keeps original ele for any out-of-CH point.
- .githooks/pre-commit: auto-corrects any added/modified track.gpx on commit and re-stages it; wired via package.json prepare -> core.hooksPath.
