Fix TS errors in the site

[mhkeller]

Fixes some typescript errors to the documentation and some helper modules.

[Copilot]

Pull request overview

This PR primarily addresses TypeScript/svelte-check issues in the documentation site and helper modules by tightening JSDoc typing, improving DOM typing in Svelte pages, and adding a site-scoped type-check command.

Changes:

• Add/adjust JSDoc annotations and a few small runtime-safe casts to satisfy checkJs/TypeScript across routes and helper modules.
• Add a dedicated check:site command (scripts/check-site.js) plus jsconfig.site.json to type-check site code while excluding library and demo/example content.
• Replace a dependency helper (readdirFilterSync from indian-ocean) with a small local implementation in the components JSON endpoint.

Reviewed changes

Copilot reviewed 26 out of 26 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/routes/guide/+page.svelte	Adds DOM/JSDoc typing and safer container guards.
src/routes/guide.json/+server.js	Types cached getSections() result.
src/routes/example/[slug]/+page.svelte	Adds JSDoc typings for markdown/highlight helpers.
src/routes/example/[slug].json/+server.js	Adds JSDoc param typing to helpers used to parse example files.
src/routes/example-ssr/[slug]/+page.svelte	Adds JSDoc typings for markdown/highlight helpers.
src/routes/example-ssr/[slug].json/+server.js	Adds JSDoc param typing and RequestHandler typing.
src/routes/components/+page.svelte	Adds JSDoc typings and DOM typing/guards for TOC behavior.
src/routes/components/[slug]/+page.svelte	Adds JSDoc typings in parsing/format helpers.
src/routes/components/[slug].json/+server.js	Removes indian-ocean usage and adds local readdirFilterSync + more JSDoc typing.
src/routes/api/guide-sections.json/+server.js	Types cached getSections() result.
src/routes/_site-components/Nav.svelte	Adds JSDoc typing for slimName.
src/routes/_site-components/GuideContents.svelte	Adds JSDoc typing for sections.map(...).
src/routes/_site-components/DownloadComponentBtn.svelte	Adds JSDoc typing for modules.map(...).
src/routes/_site-components/DownloadBtn.svelte	Adds JSDoc typing for reducers/loops and dependency lookups.
src/_modules/slugify.js	Adds function JSDoc signature for better TS inference.
src/_modules/processMarkdown.js	Adds function and local variable JSDoc typing.
src/_modules/hljsDefineSvelte.js	Adds JSDoc typing for hljs parameter.
src/_modules/getSections.js	Adds JSDoc typing, improves reduce typing, and adjusts hash lookup typing.
src/_modules/downloadBlob.js	Adds JSDoc typing and casts for Blob handling.
src/_modules/constructReplLink.js	Adds JSDoc typing and null-safe filename extraction.
src/_modules/cleanTitle.js	Adds function JSDoc signature for better TS inference.
src/_modules/calcThresholds.js	Adds JSDoc and defaults n to avoid undefined math.
src/_modules/arrowUtils.js	Adds JSDoc typing/casts to satisfy checkJs.
scripts/check-site.js	New script to run and post-filter svelte-check results for site-only code.
package.json	Adds check:site script entry.
jsconfig.site.json	Adds site-only jsconfig extending base config with excludes.

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[Copilot]

Pull request overview

Copilot reviewed 27 out of 27 changed files in this pull request and generated 4 comments.