docs(readme): refléter la session de groupe unique (P6) et le démarrage sur branche principale

- Groupes de travail : une seule session Claude couvrant tous les repos via
  --add-dir (au lieu d'une session par repo).
- Sessions démarrables sur la branche principale ou n'importe quel worktree.
- Réponse aux dialogues (options + Deny) plutôt qu'« approuver/refuser ».
- Miroir EN/FR.

README.md

@@ -10,7 +10,7 @@
   <strong>English</strong> · <a href="README.fr.md">Français</a>
 </p>
 
-**Status: MVP.** The worktree-first dashboard, session discovery & resume, multi-repo worktree lifecycle, live session states, the web terminal, and mobile supervision (installable PWA, Web Push when a session needs you, approve/deny without opening a terminal), and work groups (run several related repos at once) are implemented and tested.
+**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.
 
 ---
 
@@ -30,8 +30,8 @@ A single Node.js daemon you run on your dev machine (`npx @johanleroy/git-arbore
 - **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.
 - **Web terminal** — full xterm.js terminal to every managed session, surviving browser disconnects.
-- **Supervision from your phone** — installable PWA with push notifications when a session needs you; approve/deny a prompt without opening a terminal.
-- **Work groups** — bundle related repos (e.g. an API, its web frontend and a shared library) into a named group to work on them at once: a unified view of all their worktrees and sessions, a side-by-side multi-terminal grid, and a one-click "cross-repo feature" that creates the same branch worktree (and optionally a Claude session) across every repo in the group.
+- **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.
 
 ---
 
@@ -100,9 +100,9 @@ node packages/server/dist/index.js
 
 1. **Add a repository.** From the dashboard, register a local git repo by its path. Optionally configure **post-create hooks** (e.g. `npm ci`, `cp ../.env .env`) that run automatically every time you create a new worktree for that repo.
 2. **Create or adopt worktrees.** Spin up a new worktree + branch in one click (hooks run for you), or adopt a worktree you created by hand. Each worktree shows its branch, ahead/behind, and dirty-file count.
-3. **Start or resume a session.** Launch a Claude Code session on a worktree, or resume one that was started in your terminal — Arboretum discovers existing sessions automatically and always resumes them in their original working directory.
+3. **Start or resume a session.** Launch a Claude Code session on the repo's main branch or any worktree, or resume one that was started in your terminal — Arboretum discovers existing sessions automatically and always resumes them in their original working directory.
 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. Approve or deny the prompt straight from the notification UI — no terminal required.
+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.
 
 ## Remote access from your phone