Summary

When using DateRangeRequiredFilter or DateRangeFilter with configureMondayFirst(true), the date range picker displays Tuesday as the first column in the week grid. If I set configureMondayFirst(false), the first column is Monday as expected.
This suggests an inversion or off-by-one issue in the front-end calendar week-start logic when Monday-first is enabled.

Environment

• Sharp: v9.10.1
• Laravel: v12.32.5
• PHP: constrained by Sharp to 8.3.|8.4. (project runs on PHP 8.4 in our environment)
• Timezone: Europe/Paris (from config/app.php)
• Laravel locale: fr (from config/app.php)
• Carbon: bundled via Laravel ^3.8.4

Note: The behavior was reproduced in multiple browsers; it does not seem browser-specific.

Affected components

• Filters: Code16\Sharp\Filters\DateRangeRequiredFilter, Code16\Sharp\Filters\DateRangeFilter

Minimal configuration that triggers the bug

use Carbon\Carbon;
use Code16\Sharp\Filters\DateRangeRequiredFilter;
use Code16\Sharp\Filters\DateRange\DateRangePreset;

class ExpenseDateFilter extends DateRangeRequiredFilter
{
    public function buildFilterConfig(): void
    {
        $this
            ->configureLabel('Date')
            ->configureKey('expense_date')
            ->configureMondayFirst(true) // problem manifests here
            ->configureShowPresets(true, [
                DateRangePreset::make(Carbon::now()->startOfWeek(), Carbon::now()->endOfWeek(), 'This week'),
                DateRangePreset::make(Carbon::now()->subWeek()->startOfWeek(), Carbon::now()->subWeek()->endOfWeek(), 'Last week'),
                DateRangePreset::make(Carbon::now()->startOfMonth(), Carbon::now()->endOfMonth(), 'This month'),
            ]);
    }

    public function defaultValue(): array
    {
        return [
            'start' => Carbon::now()->startOfWeek(),
            'end' => Carbon::now()->endOfWeek(),
        ];
    }
}

Note: In our project we also tested with configureMondayFirst(false); with false, the grid starts on Monday (which is counterintuitive), and with true it starts on Tuesday.

Steps to reproduce

1. Create a DateRangeRequiredFilter (or DateRangeFilter) and call configureMondayFirst(true).
2. Set any default or preset range (e.g., current week using Carbon::now()->startOfWeek()/endOfWeek()).
3. Load the list view with the filter.
4. Observe the date range picker grid: the first column is Tuesday, not Monday.

Observed behavior

• With configureMondayFirst(true) on filters, the calendar grid starts on Tuesday.
• With configureMondayFirst(false), the grid starts on Monday.

This looks like an inversion/misalignment in the Monday-first handling on the front-end.