fix(row-selection): correct select-all checkbox state for manual pagination

[rahulpatwa1303]

Description

Fixes incorrect header checkbox state when using manual pagination.

When only the current page rows are selected, the select-all checkbox
was shown as checked even though only a subset of the total dataset
was selected. The checkbox now correctly reflects global selection
state and shows an indeterminate state.

Reproduction

• Enable manualPagination
• Provide rowCount
• Select all rows on the first page
• Navigate to another page

Expected

Header checkbox shows indeterminate state.

Actual (before)

Header checkbox appeared checked.

Notes

This change does not affect non-manual pagination behavior.

[vercel]

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