[BUGFIX] Fix the checkbox sync select-all state and preserve selection

[aleRibeiro0209]

⚡ PowerGrid - Pull Request

• Bug fix
• Enhancement
• New feature
• Breaking change

Description

Fixes the "select all" checkbox so its state always reflects the actual row selection, and prevents the selection from being cleared when the per-page size changes.

Previously the header checkbox relied on the two-way bound checkboxAll property (wire:model + wire:click), which could desync from the real state of the row checkboxes and never rendered an indeterminate state. On top of that, changing the per-page size triggered a page reset that wiped the current selection.

Header checkbox driven by the real row state — a new pgSelectAll Alpine component inspects the row checkboxes and updates the header accordingly:

<input
    x-data="pgSelectAll"
    class="{{ theme('table.checkbox.input') }}"
    type="checkbox"
    x-on:change="$wire.selectCheckboxAll($event.target.checked)"
>

- checked when all enabled rows are selected.
- indeterminate when some (but not all) rows are selected.
- Re-evaluated on every row change and after each Livewire commit.

Explicit intent sent to the server — the front-end now passes the checked value instead of depending on the two-way bound property:

public function selectCheckboxAll(?bool $checked = null): void
{
    if ($checked !== null) {
        $this->checkboxAll = $checked;
    }
    // ...
}

Implementation notes:
- New resources/js/components/pg-select-all.js (registered in components/index.js) manages the checked/indeterminate state and listens to a pg-select-all:refresh event dispatched after each Livewire commit.
- checkbox-all.blade.php (shared structure view + tailwind view) swaps wire:model/wire:click for x-data="pgSelectAll" + x-on:change="$wire.selectCheckboxAll($event.target.checked)".
- Checkbox::selectCheckboxAll() accepts an optional ?bool $checked to receive the explicit intent from the front-end.
- PowerGridComponent::resetToFirstPage() short-circuits when already on page 1, so changing the per-page size no longer clears the current selection.
- Added tests covering the page-1 short-circuit, selection preserved across per-page changes, and the explicit checked argument.

Related Issue(s):

Documentation

 This PR requires Documentation update?

- [ ] Yes
- [x] No
- [ ] I have already submitted a Documentation pull request.