chore: convert repo to pnpm monorepo (packages/desktop, muyajs, website) - #4302

Merges 37 upstream commits into the fork, including the pnpm monorepo
conversion (marktext#4302), muya TS rewrite migration (marktext#4314), website package,
and fixes through CJK emphasis boundary (marktext#4355).

Conflict resolutions:
- package.json: adopt upstream monorepo root shell; drop fork's
  root-level deps block; move 4 fork-added deps (diff, @types/diff,
  markdown-it, @types/markdown-it) to packages/desktop/package.json
- build.yml: keep both fork's workflow_dispatch+dynamic-matrix and
  upstream's paths-ignore: packages/muya/**
- wsl.ts, comparisonPane.vue, wsl-paths.spec.ts: accepted git's rename
  detection — files live under packages/desktop/ in the monorepo layout
- docs/dev/FORK_PLAN.md: kept at repo-root docs/dev/ (private fork doc,
  not published website content)
- pnpm-lock.yaml: regenerated via pnpm install

Two regressions from the monorepo conversion (#4302, #4314) broke
`pnpm run build:mac/win/linux` outside CI:

- electron is only a devDependency of packages/desktop. With pnpm
  workspaces, `shamefully-hoist=true` does not surface it at the
  workspace root, so electron-vite's `require.resolve('electron/
  package.json')` (resolved from its own .pnpm location) fails. Pin
  electron at the workspace root so it is hoisted into root
  node_modules.

- packages/muyajs/lib/renderers/index.js dynamically imports
  flowchart.js, mermaid and vega-embed, but these were only declared
  in packages/desktop. Vite/Rollup can resolve them when bundling the
  renderer alone, but in a strict pnpm layout muyajs cannot see its
  sibling's deps. Declare them as muyajs's own dependencies so each
  package owns what it imports.

Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>

…te) (marktext#4302)

* chore(monorepo): introduce pnpm workspace and extract muya as packages/muyajs

Add `packages/*` to pnpm-workspace.yaml and relocate src/muya into
packages/muyajs (name: @marktext/muyajs, private). Aliases in
electron.vite.config.ts, vitest.config.ts and tsconfig.base.json now
point at packages/muyajs, and the eslint scopes that targeted src/muya
have been updated to match. Consumer import paths ('muya/lib/...') are
unchanged.

This lays the ground for a future packages/muya holding muya-v2 from
https://github.com/marktext/muya without colliding with the current
engine.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* chore(monorepo): move Electron desktop app into packages/desktop

Relocate the desktop app (src/, electron.vite.config.ts, electron-builder.yml,
tsconfig*, vitest.config.ts, build/, static/, test/, patches/) into
packages/desktop. The root package.json is now a workspace orchestrator that
proxies every CI-facing script through `pnpm --filter marktext ...`, so the
existing CI workflows continue to invoke `pnpm <script>` from the repo root
without any working-directory changes. electron-builder writes its artifacts
to ../../dist via directories.output, keeping the upload-artifact globs
pointed at `dist/*` valid.

Workspace-shared tooling (ESLint, Prettier, tsx, license-checker) stays at
the root; all Electron/Vue/build-time deps move into the desktop package.
@marktext/muyajs is added as a workspace:* dependency, and the muya alias in
electron.vite/vitest/tsconfig now resolves to ../muyajs.

scripts/postinstall.ts, minify-locales.ts, generateThirdPartyLicense.ts and
validateLicenses.ts now operate against packages/desktop (its node_modules,
patches/, static/locales/ and build/) since workspace-local deps are not
hoisted to the root. minify-locales drops a dead fs.existsSync probe — let
readdirSync surface its own ENOENT.

packages/muyajs/package.json gains the runtime deps muya imports from npm
(github-markdown-css, katex, dompurify, snabbdom, …) so Node module
resolution stays inside the workspace instead of escaping into the parent
directory's node_modules.

ESLint: widen out/dist ignores to **/out/** and **/dist/** (the new
package-local output dirs), disable the deprecated core no-extra-semi
(defer to @stylistic/no-extra-semi from neostandard, which understands
leading-semi standard guards), and update the muya/desktop globs.

License check: derive the workspace exclusion list from each package's
own package.json at runtime so version bumps stay in sync automatically.
@marktext/file-icons remains pinned because it's a published dep that
license-checker fails to detect (MIT).

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* chore(monorepo): import marktext-website as packages/website

Snapshot the marktext-website source from its standalone repo into
packages/website (src/, public/, build/, index.html, vite.config.ts,
tsconfig*, package.json, README.md, .gitignore). The website keeps its
existing name (marktext-website), its own React 18 / Vite 5 toolchain
and continues to depend on @muyajs/core from npm — local muya
consumption can be wired in a follow-up if needed.

History was not preserved (single import commit) per the agreed plan.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* docs(claude): reflect monorepo layout in CLAUDE.md

Update Tech Stack, Directory Structure, Development Workflow, Testing,
Architecture, and Important Build Notes sections to describe the new
packages/{desktop,muyajs,website} layout: where files moved, how the
root scripts proxy to packages/desktop via pnpm --filter, the updated
muya alias and workspace dep wiring, electron-builder's `../../dist`
output redirection, and the patches/ relocation.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>