feat(site,docs): aligne le site vitrine et la doc sur l'app « Emerald »

Site (packages/site) : adopte le design system Emerald (polices Inter +
JetBrains Mono variables, tokens sémantiques, thème clair/sombre + bascule)
et met les mockups à jour sur l'app réelle.

- style.css : tokens Emerald (@theme sombre + override html[data-theme=light]) ;
  lib/theme.ts + ThemeToggle.vue + anti-FOUC index.html ; sweep des couleurs
  brutes vers les tokens dans toutes les sections.
- Mockups fidèles à l'IDE multi-projet : HeroMockup (rail ActivityBar au lieu
  de la sidebar large + v obsolète retirée), ShowcaseSection (supervision au
  lieu du dashboard worktree-first, onglets mobiles réels), WorkspaceShowcase
  (diff-add/del, bouton commit accent-solid) ; framing « worktree-first »
  résiduel levé (i18n).
- og-cover.png rafraîchi (carte Emerald).

Docs : README.md + README.fr.md (retrait « Status: MVP », ajout du langage
Emerald + thème clair/sombre/système, VSIX 0.2.0 -> 0.3.0, section Screenshots),
vscode README (VSIX 0.3.0), brand README (thème clair), CHANGELOG daemon 3.2.0.
Captures IDE sombre + clair (brand/screenshot-ide-*.png).

README.md

@@ -10,12 +10,28 @@
   <strong>English</strong> · <a href="README.fr.md">Français</a>
 </p>
 
-**Status: MVP.** The worktree-first dashboard, session discovery & resume, multi-repo worktree lifecycle, sessions on your main branch or any worktree, live session states, the web terminal, mobile supervision (installable PWA, Web Push when a session needs you, answer a prompt without opening a terminal), and work groups (drive several related repos from a single Claude session) are implemented and tested.
+Session discovery & resume, multi-repo worktree lifecycle, sessions on your main branch or any worktree, live session states, the web terminal, mobile supervision (installable PWA, Web Push when a session needs you, answer a prompt without opening a terminal), and work groups (drive several related repos from a single Claude session) are all implemented and tested.
 
 The latest milestone turns Arboretum into a real **multi-project AI IDE**: a single workspace (route `/ide`, the default view on desktop) that holds **all** your open projects at once, no more one IDE window per project. A single left tree (project, then main checkout and worktrees, then Claude session), a tabbed Monaco editor at the center (several files from different projects side by side, inline diffs), Claude terminals in a bottom dock, and Git / Sessions / Groups panels via an activity bar. It ships both as a **native desktop app** (Linux, Windows, macOS) and the same web UI, backed by a real-time file-system watcher, selective staging / discard / amend / fetch / pull, automatic session archival, real-time settings sync, and encrypted remote git services (GitHub / GitLab / Gitea) with HTTPS clone.
 
 ---
 
+## Screenshots
+
+<p align="center">
+  <img src="brand/screenshot-ide-dark.png" alt="Arboretum, the multi-project AI IDE (dark theme)" width="900">
+</p>
+
+<p align="center">
+  <em>One workspace for every project: a unified tree, a tabbed Monaco editor with inline diffs, and docked Claude terminals. Dark and light themes.</em>
+</p>
+
+<p align="center">
+  <img src="brand/screenshot-ide-light.png" alt="Arboretum, the multi-project AI IDE (light theme)" width="900">
+</p>
+
+---
+
 ## The problem
 
 Working with AI coding agents changed how we use git: one feature = one worktree = one Claude Code session, several of them in parallel. But the tooling didn't follow:
@@ -28,7 +44,7 @@ Working with AI coding agents changed how we use git: one feature = one worktree
 
 A single Node.js daemon you run on your dev machine (as a native desktop app, or via `npx @johanleroy/git-arboretum`), serving a UI usable from your desktop, phone or tablet:
 
-- **Worktree-first, multi-repo dashboard**: every worktree of every registered repo, with its git state (branch, ahead/behind, dirty files) *and* the state of its Claude Code session (busy / waiting for input / idle / resumable).
+- **Multi-repo worktree dashboard**: every worktree of every registered repo, with its git state (branch, ahead/behind, dirty files) *and* the state of its Claude Code session (busy / waiting for input / idle / resumable).
 - **Full worktree lifecycle**: create (with per-repo post-create hooks: `npm ci`, copy `.env`…), adopt worktrees created by hand, delete with guardrails, prune orphans.
 - **Session discovery & resume**: sessions you launched in your own terminal show up automatically; resume dead ones, observe or fork live ones. Never corrupts a live session. Hide the old ones that clutter the list (one click clears the whole external history; they stay resumable).
 - **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.
@@ -129,6 +145,7 @@ Beyond supervising, Arboretum is a full **multi-project IDE** (route `/ide`, the
 - **Terminal dock.** Claude session terminals live in a bottom dock with one tab per session; open several at once (across projects), answer a waiting prompt right there. Terminals survive tab switches and browser disconnects.
 - **Git panel.** Stage or unstage individual files, discard changes, write a message and **commit** (everything or just what's staged), **amend** the last commit (refused once pushed), then **fetch**, **pull** (fast-forward or rebase) and **push**. Detailed staged / unstaged / conflict counts and the last commit stay current via a **real-time file-system watcher**, so the view updates the moment a Claude session touches a file.
 - **Deep links & mobile.** `/workspace/:repoId/:wt` still opens a specific worktree straight in the IDE (used by the VS Code extension). On mobile the IDE degrades to a single panel, and the worktree dashboard and session views remain the installable supervision PWA.
+- **Light or dark, your call.** A clean, consistent visual language (the "Emerald" design system: Inter + JetBrains Mono, an emerald accent) with a **light / dark / system** theme toggle remembered across sessions. The Monaco editor, the terminals and the diffs all follow the active theme.
 
 Like every git action in Arboretum, these run **as you** (the daemon runs under your account), consistent with the security model: a web terminal is remote code execution by design.
 
@@ -146,10 +163,10 @@ 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-0.2.0.vsix
+cd packages/vscode && npx @vscode/vsce package --no-dependencies   # → git-arboretum-0.3.0.vsix
 ```
 
-Then install it via **Extensions: Install from VSIX…** (or `code --install-extension git-arboretum-0.2.0.vsix`), run **Arboretum: Sign In** and paste a token. Full details in [`packages/vscode/README.md`](packages/vscode/README.md).
+Then install it via **Extensions: Install from VSIX…** (or `code --install-extension git-arboretum-0.3.0.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