[Feature Request] Allow scenarios to start with When or Then

[Kahoulam]

Description

Currently, a scenario must start with Given. In real Gherkin scenarios, you can start with any keyword (Given, When, or Then), but the current DSL forces you to always use Given first:

// Current: Must start with Given
Bdd(feature)
    .scenario('Login')
    .given('user is registered')
    .when('user logs in')
    .then('access granted');

Trying to start with When or Then directly causes a compile error.

Proposed API

// Should allow starting with any keyword
Bdd(feature)
    .scenario('Login')
    .when('user logs in')
    .then('access granted');

Bdd(feature)
    .scenario('Test')
    .then('result happens');

Expected Behavior

Just like in Gherkin/Cucumber, a scenario should be able to start with any step keyword, not just Given.