v1.2.0:4 — make avg. watts a first-class SetLog field

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.

start9/0.4/docker_entrypoint.sh

@@ -72,6 +72,11 @@ if command -v sqlite3 >/dev/null 2>&1 && [ -f "$DB_PATH" ]; then
     sqlite3 "$DB_PATH" "ALTER TABLE SetLog ADD COLUMN customMetrics TEXT;"
   fi
 
+  if ! sqlite3 "$DB_PATH" "PRAGMA table_info('SetLog');" 2>/dev/null | grep -q "|watts|"; then
+    log "adding missing column SetLog.watts"
+    sqlite3 "$DB_PATH" "ALTER TABLE SetLog ADD COLUMN watts INTEGER;"
+  fi
+
   if ! sqlite3 "$DB_PATH" "PRAGMA table_info('Workout');" 2>/dev/null | grep -q "|deletedAt|"; then
     log "adding missing column Workout.deletedAt"
     sqlite3 "$DB_PATH" "ALTER TABLE Workout ADD COLUMN deletedAt DATETIME;"