fix: only call afterNavigate once on start when SSR is disabled

[teemingc]

fixes #13573

This PR changes the unexpected behaviour of afterNavigate being called twice when SSR is disabled to only once (same as when SSR is enabled). It was being called twice: once with type 'enter' and again with type 'goto' because we initialised the app and used goto under the hood to render the page client-side. Now, it should only be called once with type 'enter'. This also adjusts the docs to state that a navigation with type 'enter' is when the app starts and not just when it's hydrated.

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🦋 Changeset detected

Latest commit: 1a183bf

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@sveltejs/kit	Patch

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-13593-svelte.vercel.app/

[dummdidumm]

looks good, once you've answered my question on the code you can self-merge 👍

[dummdidumm]

is this necessary? When could started be true but the type enter?

[teemingc]

I think this was only added for type narrowing. TypeScript doesn’t know that we won’t use navigate with the “enter” navigation type after the app has started. Meanwhile, navigating.current has been typed to never have the “enter” navigation type.