feat(host)!: remove the Node host and node-pty (#76 phase 4b)

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## 2026-10-27
 
+- [host] Rust host phase 4b (#76, ADR 0004): the Node host and node-pty are gone. Removed `src/host/index.ts`, the `host.js` build entry, `settings.nodeHost` (Settings → Advanced "Use the Node host") and `node-pty` with its rebuild (`postinstall`, `trustedDependencies`, `asarUnpack`, `npmRebuild: false`); `bun install` builds no native module. `hostBinary()` finds the binary for the app and `wraithgrid host-stdio`; a build without it can't start terminal panes, so `bun run dev`/`test:e2e` run cargo first. The Node host's server/screen/pty manager moved to `tests/support/node-host/` as the in-process host of the client unit tests (fake ptys); the parity suite runs the Rust host only, with headless xterm as the reference for resizes (30 tests). Linux package checks test `wraithgrid-host --version` instead of node-pty; README build requirements are Rust + a C linker (files: src/host/_, src/main/{host-start,app,cli-entry,ipc,pane-host,pane-router,spawn-resolve}.ts, src/shared/{types,schema,ipc-contract}.ts, src/renderer/{app/store.ts,components/SettingsView.tsx}, tests/support/node-host/_, tests/host/_, tests/unit/_, tests/e2e/{rust-host,machines}.spec.ts, package.json, bun.lock, electron.vite.config.ts, electron-builder.yml, scripts/_, README.md, docs/_)
 - [cli] `wraithgrid send` marks the pane as having a conversation, as Enter typed in it does, so a restart resumes it (H6 follow-up): a new gui relay action `sent` (no host protocol change; no window open, nothing to mark); docs/TODO.md cleared of six items that had already shipped (#39–#41, file attach, delete chat confirm, sign-in dialog) (files: src/shared/ipc-contract.ts, src/main/{cli,ipc}.ts, src/renderer/app/store.ts, tests/unit/cli.test.ts, tests/e2e/cli.spec.ts, docs/TODO.md)
 - [host] Old Rust hosts no longer pile up on ssh machines (#76): each connect touches this version's `~/.wraithgrid/bin/wraithgrid-host-<version>` (its date says when it was last used) and deletes other versions unused for 30 days, so two Wraithgrid versions sharing a machine don't copy theirs over again on every connect; a host still running a deleted one keeps running. `command find`, since a fish config can shadow `find` (this machine's does); tested for real in sh and fish (files: src/main/remote-bin.ts, tests/unit/remote-host.test.ts)
 - [host] Rust host phase 4a (#76, ADR 0004 Accepted): terminal panes run in the Rust host by default on Linux, macOS and Windows. `settings.nodeHost` (Settings → Advanced "Use the Node host", off; `WRAITHGRID_NODE_HOST=1` in tests) replaces `rustHost`: every config saved that as false, so it is dropped on load and everyone moves to Rust; a build without the binary runs the Node host. `bun run test:e2e` builds the Rust host first, so e2e runs the default; `rust-host.spec` checks both ways (files: src/shared/{types,schema}.ts, src/main/app.ts, src/renderer/components/SettingsView.tsx, tests/e2e/{rust-host,machines}.spec.ts, package.json, docs/adr/0004-rust-pty-host.md, docs/CONTEXT.md)

README.md

@@ -448,32 +448,33 @@ bar, or the command palette) covers the rest:
 
 - Node.js 22.12 or newer, and Bun 1.4 or newer (<https://bun.sh>); Bun installs and runs the
   scripts, the tools themselves still run on Node
-- A C++ toolchain for the `node-pty` native module:
-  - Arch: `sudo pacman -S --needed python make gcc`
-  - Ubuntu, Debian, Kali: `sudo apt install python3 make g++`
-  - Fedora: `sudo dnf install python3 make gcc-c++`
-  - Windows: Visual Studio Build Tools with "Desktop development with C++", and Python 3
+- Rust (stable, <https://rustup.rs>) for the background host in `host-rs/`, with the C
+  linker it uses:
+  - Arch: `sudo pacman -S --needed gcc`
+  - Ubuntu, Debian, Kali: `sudo apt install gcc`
+  - Fedora: `sudo dnf install gcc`
+  - Windows: Visual Studio Build Tools with "Desktop development with C++"
   - macOS: Xcode Command Line Tools (`xcode-select --install`)
 - To build a Fedora `.rpm` on another distro: `rpmbuild` (`rpm-tools` on Arch, `rpm` on
   Ubuntu). The pacman package needs `bsdtar` (`libarchive-tools` on Ubuntu).
 
 ```sh
-bun install                    # installs deps and rebuilds node-pty for Electron
-bun run dev                    # run with hot reload
+bun install                    # installs deps (no native Node modules to build)
+bun run dev                    # builds the Rust host, then runs with hot reload
 bun run dist:linux:portable    # all Linux packages, built in Docker on Ubuntu 22.04
 bun run dist:win               # Windows installer (run on Windows)
 bun run dist:mac               # macOS .dmg and .zip, Apple Silicon and Intel (run on a Mac)
 ```
 
 Bun runs install scripts only for the packages in `trustedDependencies` in `package.json`
-(`electron`, `esbuild`, `node-pty`); `bunfig.toml` keeps a flat `node_modules` for electron-builder.
+(`electron`, `esbuild`); `bunfig.toml` keeps a flat `node_modules` for electron-builder.
 
 <details>
 <summary><b>Why the portable build?</b></summary>
 
 <br />
 
-`node-pty` compiles against the build machine's glibc. A package built on a rolling distro
+The Rust host links against the build machine's glibc. A package built on a rolling distro
 (Arch, current Fedora) only runs on distros at least as new. `dist:linux:portable` builds on
 Ubuntu 22.04 (glibc 2.35) inside Docker, so one set of packages runs on Ubuntu 22.04+,
 Debian 12+, Kali, Fedora and Arch. `scripts/test-linux-packages.sh` then installs each package