fix: discard a consumed preloaded redirect before following it

[Nic-Polumeyv]

In runtime/client/client.js, _preload_data stores every load_route result in load_cache and load_route hands the entry back whenever the intent id matches. navigate only clears load_cache on the commit path, after history.pushState; the redirect branch recurses into navigate for the redirect target and returns before that. So when a preloaded route redirects and a later hop of the same navigation comes back to it (a gate: /dashboard redirects to /select until a flag is set, /select sets it and redirects to /dashboard), the cached redirect is replayed without a fetch on every return until the 20-redirect limit renders the 500 page.

Discard the consumed entry in the redirect branch before recursing, keyed on intent.id so a preload of a different route (such as the redirect target) survives. The first hop is still served from the preload; anything after it loads fresh.

Fixes #16484.

Replaces #16930. Thank you for the attempt @bmdavis419, big fan of your content.

[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from 6a9437d:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/6a9437da6b85f0182d724b6b34170b41297db8fd

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16955

[changeset-bot]

🦋 Changeset detected

Latest commit: 6a9437d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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@sveltejs/kit	Patch

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-16955-svelte.vercel.app/

[Rich-Harris]

sad that we can't induct @bmdavis419 as a contributor — next time! — but happy for the fix