* Broken dash repro
* Fix V16 migration to preserve panels when rows array is empty
- Fixed bug where panels were deleted when migrating dashboards with empty rows array
- Updated v16.go to match frontend implementation behavior
- Added test case for empty rows scenario in v16_test.go
- Renamed test files to v16.empty-rows-and-panels-array.json for clarity
- All migration tests passing (419 test cases)
