docs: documenter l'extension VS Code (README EN/FR, centre d'aide, site)

- README.md / README.fr.md : bullet dans « What Arboretum does », section dédiée
  « VS Code extension » (build/packaging VSIX, install, sign in), ligne monorepo.
- Centre d'aide in-app (help-content.ts) : item « VS Code extension » dans Integrations (EN/FR).
- Site vitrine : 9e carte de features « Native VS Code extension » (feat9, EN/FR + icône).

README.md

@@ -32,6 +32,7 @@ A single Node.js daemon you run on your dev machine (`npx @johanleroy/git-arbore
 - **Web terminal** — full xterm.js terminal to every managed session, surviving browser disconnects; truly fullscreen, with the prompt pinned to the bottom and full scrollback above.
 - **Supervision from your phone** — installable PWA with push notifications when a session needs you; answer a prompt (its options, or deny) without opening a terminal.
 - **Work groups** — bundle related repos (e.g. an API, its web frontend and its docs) into a named group, then launch **one Claude session that spans all of them at once** (via the CLI's `--add-dir`): a single conversation with one shared context working across every repo, plus a unified view of all their worktrees and a side-by-side multi-terminal grid. Group sessions can either create the same branch worktree in each repo first, or run straight on the main checkouts.
+- **VS Code extension** — a native extension (not a webview) that brings the live tree, native session terminals, waiting alerts and git actions right into your editor. See [VS Code extension](#vs-code-extension).
 
 ---
 
@@ -104,6 +105,24 @@ node packages/server/dist/index.js
 4. **Watch the live states.** Each session reports whether it's *busy*, *waiting for your input*, or *idle*. Open the **web terminal** to interact directly; it survives browser disconnects (closing the tab does not kill the session).
 5. **Supervise from your phone.** Install the PWA, and when a session flips to *waiting* you get a push notification. Answer the prompt — pick one of its options or deny it — straight from the dashboard, no terminal required.
 
+## VS Code extension
+
+Prefer to stay in your editor? Arboretum ships a **native VS Code extension** (`packages/vscode`) — not a webview. It connects to the same daemon and surfaces it with VS Code's own primitives:
+
+- A live **Repositories** and **Groups** tree (repos → worktrees → sessions) in the Activity Bar, updated in real time over the daemon's WebSocket.
+- **Native terminals**: attach to (or observe) any session in a real VS Code terminal — you get VS Code's rendering, scrollback and copy/paste for free.
+- A **status-bar** counter and native **notifications** when a session is waiting, with Yes/No answers without opening a terminal.
+- Git mutations (create worktree, commit, push, promote) and **workspace awareness** — the worktree for your open folder is highlighted, with one-click "start session / create worktree here".
+
+It is distributed as a **private VSIX**. Build and package it from the monorepo:
+
+```bash
+npm run build:vscode
+cd packages/vscode && npx @vscode/vsce package --no-dependencies   # → git-arboretum-0.1.0.vsix
+```
+
+Then install it via **Extensions: Install from VSIX…** (or `code --install-extension git-arboretum-0.1.0.vsix`), run **Arboretum: Sign In** and paste a token. Full details in [`packages/vscode/README.md`](packages/vscode/README.md).
+
 ## Remote access from your phone
 
 Arboretum binds to `127.0.0.1` by default and **refuses** to bind to a non-loopback address without an explicit override. The recommended (and safe) way to reach it from other devices is **[Tailscale Serve](https://tailscale.com/kb/1242/tailscale-serve)** — valid HTTPS, tailnet identity, no open ports:
@@ -235,7 +254,7 @@ Arboretum wraps the **interactive** Claude Code CLI in a PTY — the same thing
 
 ## Development
 
-Arboretum is an npm-workspaces monorepo: `@arboretum/shared` (WS/REST protocol, source of truth), `@johanleroy/git-arboretum` (the Fastify daemon, the published package), and `@arboretum/web` (the Vue 3 SPA).
+Arboretum is an npm-workspaces monorepo: `@arboretum/shared` (WS/REST protocol, source of truth), `@johanleroy/git-arboretum` (the Fastify daemon, the published package), `@arboretum/web` (the Vue 3 SPA), and `git-arboretum` (the VS Code extension — built separately with `npm run build:vscode`).
 
 ```bash
 npm run build        # build shared → server → web (order matters)