fix: solve shift arrow multi selection issue #5146

[fangsmile]

Summary

• fix keyboard multi-selection with Shift + Arrow keys so the range keeps expanding
• add a dedicated issue-5146 debug demo for reproduction and regression testing
• add a Rush change file for @visactor/vtable

Verification

• reproduce the issue in list-100w before the fix
• verify repeated Shift+ArrowDown expands from row 2-3 to row 2-4 after the fix
• verify repeated Shift+ArrowRight in Debug -> issue-5146 expands from col 1-2 to col 1-3
• check diagnostics for the edited files