Average watts (assault bike, rower, ski erg) was a free-text entry stuffed
into the per-set customMetrics JSON blob. Promote it to a real nullable
column, SetLog.watts, written through every set path (create / PATCH /
add-sets / import-save / account-import) and shown everywhere as
"Avg. watts" with a proper numeric input.
The column is added by the boot-time guarded ALTER in docker_entrypoint.sh
(additive, idempotent), so the version migration stays empty. Existing data
is untouched: legacy watts values remain readable from customMetrics and
migrate to the column the next time a set is saved.
Keysat