fix: deduplicate remote query starts during fork preloads

[svelte-triage-bot]

• Remote query startup was guarded only by fork-local reactive promise state, so the retained delayed start escaped the preload fork and repeated the request against prior route state.
• Preserve the isomorphic cache from #15779 and delayed active-query startup from #16014, but share startup status across fork and live views.
• Use a non-reactive startup marker while keeping per-view promises restartable; removing the delay was rejected because it regressed same-page query refresh.
• Cover one-request parameterized preloads and restarting queries after discarded preload forks across the shared query accessors.

Fixes #17370

[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from 400b574:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/400b5741529415d5989e2427cc2970dd090b71f9

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/17371

Note

This PR is from a fork. A maintainer must approve approve each commit before it can be built and installed.

[changeset-bot]

🦋 Changeset detected

Latest commit: 400b574

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

This PR includes changesets to release 1 package

Name	Type
@sveltejs/kit	Patch

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