fix: prevent 404 on llms.txt links after client-side navigation

[imlargo]

Summary

• The llms.txt link at the bottom of doc pages (and on /docs/llms) points to a route that only has a +server.ts (no +page.svelte). SvelteKit's client-side router intercepted the click and tried to render it as an SPA page, which fails since there's no page component — resulting in a client-rendered 404. A hard reload bypasses the client router entirely and hits the server route directly, which works correctly.
• Add data-sveltekit-reload to these links so they always perform a full browser navigation instead of being intercepted by the SPA router.

Test plan

• Visit a docs page (e.g. /docs/kit/adapter-cloudflare#Usage) and click the llms.txt link at the bottom, confirm it loads the file instead of a 404.
• Visit /docs/llms and click each of the listed llms*.txt links, confirm they all load correctly.

[vercel]

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