The 14 phase-related profile columns (warmup/cooldown per workout type,
plus an unused Interval pair) added more granularity than wanted. Migration
0006 drops all 14 and adds a single warmup_minutes/cooldown_minutes pair
applied uniformly to every fixed-duration workout type; Interval still
detects phases from lap data directly and ignores this setting. Restores
a simplified Phase detection section in the Profile UI with just the two
fields.
