Adding the `svelte-check` CI gate surfaced pre-existing type errors and
warnings under develop's TypeScript 6 / Svelte 5.56 bump. Fixes them so
`pnpm check` reports 0 errors / 0 warnings:
- Add `lang="ts"` to Share/Privacy (and a script to PrivacyPolicyLink) so
importers get real declarations instead of implicit `any`.
- Replace the deprecated `monaco.languages.json` with the new top-level
`monaco.json` namespace (proper API, no casts).
- Navbar: use `resolve('/', {})` instead of the deprecated `base`.
- Type the promo `component` as `Component<{ closeBanner: Snippet }>` and
MainMenu's `renderer` as `Snippet<[Omit<MenuItem, 'renderer'>]>`.
- Index-by-string casts in state.ts / Preset / DiagramDocumentationButton.
- Make Actions' clipboard handler accept an optional event.
- toggle-group: expose variant/size via getters to fix the
state_referenced_locally warning.
- Make the History e2e save/delete cases change state via a sample
diagram (deterministic) instead of editor typing.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
