Rebuild SvelteKit bits, add tsconfig.json to root

[koitsu]

Note: the tsconfig.json addition to the root of the project, specifically use of the "extends" param, ensures that we no longer get warnings like this at Node runtime:

The TypeScript option verbatimModuleSyntax is now required when using Svelte files with lang="ts". Please add it to your tsconfig.json.

[familiarcow]

Thanks @koitsu — split the spirit of this into a focused PR (#25) that:

1. Adds .svelte-kit/ to .gitignore and untracks it (the autogen rebuild here is a recurring symptom of .svelte-kit/ not being gitignored — fresh dev runs would re-introduce drift within a week)
2. Adds the root tsconfig.json you proposed, but trimmed to just verbatimModuleSyntax: true — that's the option needed to silence the warning, and we deliberately dropped strict / checkJs / isolatedModules from this PR. With strict + checkJs + allowJs, the svelte-check baseline would jump to 2319 enforced errors across 77 files (currently warnings) which is a significant policy change worth its own deliberate decision.

Verified the warning is gone after #25. Closing this in favor.