Issue #3616594: Let a site set how long the click queue waits before it posts

The wait is now yoyaku_presentation.settings:click_delay, on the booking settings screen in milliseconds.

• Where it is published: hook_js_settings_alter(), and only where the queue is actually loaded. Every surface reaches it through a library dependency rather than by naming it, so the check resolves the dependency tree. Deliberately not the library definition's own drupalSettings, which is the tidier home but is cached with the library info, so a site changing the number would go on being served the old one.
• The default stays in the JavaScript: queue.js keeps 400 as defaultDelay and falls back to it, so a site that never touches the setting behaves exactly as before.
• Tests: ClickDelayTest (kernel) covers the number travelling, travelling through a dependency, and not travelling to a page with no queue; PresentationSettingsFormTest (functional) covers the form; OfferStepperTest::testTheSiteSetsHowLongEachClickWaits (browser) covers the queue actually waiting that long, and the catch-up flush not being that number.

French translation and docs/steppers.md move with it.