Harden the Typst math renderer for upstream:

- make `@myriaddreamin/typst-ts-node-compiler` an optional peer
  dependency (kept as a devDependency for the monorepo). It is loaded
  on demand via `loadTypstCompiler()` with the same multi-root dynamic
  import + fallback strategy as `playwright-chromium`, throwing a
  helpful install hint when missing.
- own a single shared compiler instance on `utils.typstCompiler`,
  loaded only when `mathRenderer: typst`; thread it through the
  markdown pipeline, notes loader, and conditional-styles CSS injection.
- replace the brittle string-reconstruction fragment extractor with a
  single robust `<math>…</math>` regex.
- surface Typst compile errors: log the diagnostic (with Typst's hints)
  via `console.warn` and render a visible inline error placeholder
  instead of silently swallowing failures.
- regenerate the VS Code headmatter schema for `mathRenderer`.

Co-authored-by: opencode <noreply@opencode.ai>

Implement `$$ {1|3|all}` click-based line highlighting for Typst math,
matching the existing KaTeX behaviour but operating on MathML.

Typst renders multi-line equations as `<mtable class="multiline-equation">`
with one `<mtr>` per line, so highlighting is far simpler and more robust
than KaTeX's span-tree walking:

- add `collectMathmlEquationLines()` that maps each top-level
  `multiline-equation` `<mtr>` to a logical line (ignoring nested tables
  such as `cases` and matrices)
- add `TypstBlockWrapper.vue` (auto-registered from client/builtin) that
  toggles `highlighted`/`dishonored` classes on the `<mtr>` rows across
  click steps
- add `styles/typst.css` dimming non-highlighted rows
- the markdown plugin already emits `<TypstBlockWrapper>` when ranges are
  present, and raw MathML otherwise

Co-authored-by: opencode <noreply@opencode.ai>

Cover the Typst markdown-it plugin:
- inline math renders as bare `<math>` (no display attr)
- block math renders as `<math display="block">`
- block math with ranges is wrapped in `<TypstBlockWrapper>` and yields
  one `<mtr>` per aligned line
- math inside code blocks is left untransformed
- invalid math emits a visible error placeholder instead of throwing
- output is free of Vue interpolation (`{{`)
- the MathML stylesheet is extractable

Assertions use targeted `toContain` checks rather than full snapshots so
they stay stable across Typst compiler versions.

Co-authored-by: opencode <noreply@opencode.ai>

Add a 'Typst Math' section to the LaTeX feature page covering:
- enabling it via `mathRenderer: typst` and installing the optional
  `@myriaddreamin/typst-ts-node-compiler` package
- inline, block, and line-highlighting usage with Typst syntax
- a LaTeX-vs-Typst syntax cheatsheet
- a link to the official Typst math reference

Co-authored-by: opencode <noreply@opencode.ai>

Add `fonts.math` to Slidev's font config and use it when Typst math renders browser-native MathML. The resolved font stack is injected into the Typst MathML stylesheet, and configured math fonts participate in generated webfont requests like the existing sans/serif/mono families.

Document the option and regenerate the VS Code headmatter schema.

Co-authored-by: opencode <noreply@opencode.ai>