- Added null checks for overallStats.month/year in gauge charts
- Added null checks for burndown and year burndown charts
- Fixed BaseChart.vue template using undefined 'chartData' variable
- Changed :data="chartData" to :data="data" to use prop directly
Fixes console errors when viewing /budget-v2 page
Verified: 0 errors, only 1 harmless plugin warning
Refs: openspec/changes/migrate-remaining-echarts-to-chartjs
