Replace reka-ui ContextMenu usage in QueryHistory, DataGrid,
AppTabBar, ObjectBrowser, and TreeItem with the lightweight
CustomContextMenu component. This removes the last reka-ui
context menu dependencies and eliminates the performance
overhead of multiple cached ContextMenu instances.
Add useSqlHighlighter composable and integrate Shiki highlighting into
DangerConfirmDialog, QueryHistory, DataGrid (replacing regex-based
highlighting), SqlFileExecutionDialog, SchemaDiffDialog, TreeItem,
ObjectBrowser, and FieldLineageDialog. Also fix danger dialog overflow
by adding overflow-hidden to DialogContent and wrap/scroll support.