fix: filter() without an amount produces a double slash

[Baspa]

Bug

In src/Transformations/Filter.php, generateUrl() unconditionally appended the amount:

$url .= '-/filter/' . $values['name'] . '/' . $values['amount'] . '/';

When filter('adaris') is called without an amount, $values['amount'] is null, which PHP casts to an empty string, yielding -/filter/adaris// — a double slash that produces an invalid Uploadcare URL.

Fix

Conditionally omit the amount segment when it is null:

if ($values['amount'] === null) {
    $url .= '-/filter/' . $values['name'] . '/';
} else {
    $url .= '-/filter/' . $values['name'] . '/' . $values['amount'] . '/';
}

The transform() validation is unchanged — null amount is permitted.

Test added

it('omits the amount segment in filter when no amount is given', function () {
    $uuid = '12a3456b-c789-1234-1de2-3cfa83096e25';

    $url = (string) uploadcare($uuid)->filter('adaris');
    expect($url)->toContain('-/filter/adaris/');
    expect($url)->not->toContain('adaris//');

    $url = (string) uploadcare($uuid)->filter('adaris', 50);
    expect($url)->toContain('-/filter/adaris/50/');
});

Note: filter triggers automatic -/preview/ insertion (the getUrl() logic), so assertions use toContain rather than exact toBe matching.