- Updated Migration_067 to use correct SQL for double-encoded JSON
- Fixed _set_match_status_and_result to properly handle UNDER/OVER results
- When result is UNDER/OVER, store it in under_over_result field
- Extract actual fight winner from winning_outcomes JSON

The winning_outcomes column is stored as a double-encoded JSON string:
- Outer layer: JSON string (e.g., '"[\"KO2\", \"WIN1\"]"')
- Inner layer: JSON array of outcome names

The fix uses JSON_UNQUOTE(JSON_EXTRACT(JSON_UNQUOTE(winning_outcomes), '$[0]'))
to extract the first outcome from the inner array.