Add a Typst compiler alongside Quarto and LaTeX

A project whose root file is a .typ file now compiles straight to PDF with
Typst, as a third engine beside Quarto (.qmd) and latexmk (.tex). Dispatch
stays purely extension-based.

CLSI:
- New TypstRunner.js: runs `quarto typst compile <main>.typ output.pdf` (reuses
  the Typst bundled in Quarto, so no extra binary / Docker change). stderr is
  merged into output.log.
- CompileManager: _isTypstFile + a TypstRunner branch in _getRunner, and
  TypstRunner added to the isRunning check and stopCompile kill list.
- RequestParser: 'typst' added to VALID_COMPILERS.

web:
- settings.defaults: 'typ' added to validRootDocExtensions and the text
  extensions (so .typ opens in the editor); 'typst' added to safeCompilers.
- output-files: the Quarto/Typst log parser (which already understands Typst
  `error:`/`warning:` + `┌─ file:line:col` diagnostics) now also handles .typ
  compiles, so their errors/warnings populate the log tabs.

Polish:
- New-project menu: "Blank Typst project" + "Example Typst project" in both the
  main and welcome dropdowns, backed by createBasicProject/createExampleProject
  flavour 'typst', a new mainbasic.typ template and an example-project-typst
  presentation (math, an image, a table, lists).
- Compiler dropdown gains a "Typst" option (cosmetic; dispatch is by extension).

README updated: three compilers side by side, with a Writing-a-Typst-document
section.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -2,14 +2,14 @@
 
 **A collaborative real-time editor for Quarto and LaTeX presentations and documents.**
 
-Verso is a fork of [Overleaf](https://github.com/overleaf/overleaf) that adds first-class [Quarto](https://quarto.org) support alongside Overleaf's existing LaTeX toolchain. It keeps Overleaf's real-time collaboration infrastructure and runs **two compilers side by side**: `.qmd` files are built with Quarto (PDF via Typst, or HTML via RevealJS), while `.tex` files still compile with `latexmk`/TeX Live. The engine is selected automatically from the root file's extension, so Quarto and LaTeX projects coexist.
+Verso is a fork of [Overleaf](https://github.com/overleaf/overleaf) that adds first-class [Quarto](https://quarto.org) support alongside Overleaf's existing LaTeX toolchain. It keeps Overleaf's real-time collaboration infrastructure and runs **three compilers side by side**, chosen automatically from the root file's extension: `.qmd` builds with Quarto (PDF via Typst, or HTML via RevealJS), `.tex` with `latexmk`/TeX Live, and `.typ` straight through [Typst](https://typst.app). All three coexist on one server.
 
 ---
 
 ## Features
 
 - **Real-time collaboration** — multiple users editing the same `.qmd` file simultaneously, powered by Overleaf's operational-transformation engine
-- **Dual compiler** — `.qmd` files build with Quarto; `.tex` files build with `latexmk`/TeX Live. The runner is chosen by the root file's extension, so LaTeX and Quarto projects live side by side
+- **Three compilers** — `.qmd` builds with Quarto, `.tex` with `latexmk`/TeX Live, and `.typ` with Typst. The runner is chosen by the root file's extension, so Quarto, LaTeX and Typst projects live side by side
 - **Two output formats** — set `format: typst` in the YAML frontmatter for a PDF preview, or `format: revealjs` for an interactive HTML presentation rendered in an iframe
 - **Document outline** — headings (`#`, `##`, `###`) are extracted and shown in the sidebar outline panel
 - **Math, code, tables** — standard Quarto/Pandoc Markdown features all work
@@ -70,7 +70,7 @@ browser ──→ nginx:80
               └── /project/*/output/* → clsi-nginx:8080 (compiled output files)
 
 web → document-updater → Redis pub/sub → real-time → browser
-web → CLSI (quarto render / latexmk) → output files → nginx → browser
+web → CLSI (quarto render / latexmk / typst) → output files → nginx → browser
 ```
 
 Key services:
@@ -80,7 +80,7 @@ Key services:
 | `web` | HTTP API, React frontend, auth, project management |
 | `real-time` | WebSocket layer, live cursor and edit sync |
 | `document-updater` | Operational transformation, Redis pub/sub |
-| `clsi` | Compiler — runs `quarto render` (`.qmd`) or `latexmk` (`.tex`) and serves output |
+| `clsi` | Compiler — runs `quarto render` (`.qmd`), `latexmk` (`.tex`) or `typst` (`.typ`) and serves output |
 | `docstore` | Document text storage (MongoDB) |
 | `filestore` | Binary file storage (S3 or local) |
 | `project-history` | Change history and version tracking |
@@ -123,6 +123,14 @@ point; **Blank LaTeX project** gives you an empty `main.tex`.
 > extra packages may not build out of the box yet — see `server-ce/Dockerfile-base`
 > for how to switch to a fuller TeX Live scheme.
 
+## Writing a Typst document
+
+A project whose root file is a `.typ` file compiles directly to PDF with
+[Typst](https://typst.app) — fast, modern markup with a real scripting
+language. No extra install is needed: Verso drives the Typst that ships inside
+Quarto (`quarto typst compile`). Use the **Blank Typst project** or **Example
+Typst project** entries in the *New project* menu to get started.
+
 ## Environment variables
 
 Verso inherits all of Overleaf's environment variables (prefixed `OVERLEAF_`).