grim7/12/2026, 11:09:49 PM

- add a vertical timeline line threading every step's status dot into one
  connected rail (StepRail): the line runs the full row height behind the dots
  and is clipped at the first/last dot so it never overshoots the ends.
- shrink the duration badge (w-14 → w-11); it was reserving more width than the
  ms value needs and pushing the status chip left, opening a big gap.

Checks: typecheck, biome, boundaries, 204 tests.

Parent53c8e4e